SteamOS comes with the following packages pre-installed. All but ten are standard ArchLinux packages:
jupiter-hw-support
jupiter-legacy-support
steam-im-modules
steam-jupiter-stable => Steam Client
steamdeck-kde-presets => Self explanatory
steamos-atomupd-client-git => Atomic update utility
steamos-customizations-jupiter => Main package containing SteamOS custom scripts
=> Also comes with custom configs for Dracut and RAUC
steamos-devkit-service => Lets devs debug software from their PC - https://gitlab.steamos.cloud/devkit
steamos-efi => Self explanatory; unknown why this is a separate package
steamos-netrc => Contains the default .netrc file at /etc/skel/.netrc. Credentials inside.
accounts-qml-module
accountsservice
acl
adobe-source-code-pro-fonts
adwaita-cursors
adwaita-icon-theme
aha
alsa-card-profiles
alsa-lib
alsa-plugins
alsa-topology-conf
alsa-ucm-conf
alsa-utils
amd-ucode
anthy
aom
appstream
appstream-qt
arch-install-scripts
archlinux-appstream-data
archlinux-keyring
argon2
ark
aspell
aspell-en
assimp
at-spi2-core
atkmm
atomupd-daemon-git
attica
attr
audit
avahi
baloo
baloo-widgets
base
bash
bash-bats
bash-completion
binutils
bluedevil
bluez
bluez-libs
bluez-plugins
bluez-qt
bluez-utils
bolt
boost-libs
breakpad
breeze
breeze-grub
breeze-gtk
breeze-icons
brotli
btop
btrfs-progs
bubblewrap
bzip2
ca-certificates
ca-certificates-mozilla
ca-certificates-utils
cairo
cairomm
cantarell-fonts
caps
casync
catatonit
cdparanoia
cfitsio
cifs-utils
clinfo
confuse
conmon
containers-common
convertlit
coreutils
cpupower
criu
crun
cryptsetup
curl
dav1d
db
db5.3
dbus
dbus-python
dconf
default-cursors
desktop-file-utils
desync
device-mapper
diffutils
ding-libs
discount
discover
distrobox
djvulibre
dmidecode
dnssec-anchors
dolphin
dos2unix
dosfstools
double-conversion
drkonqi
drm_info
ds-inhibit
duktape
e2fsprogs
ebook-tools
editorconfig-core-c
efibootmgr
efivar
elfutils
ell
enchant
evtest
exfat-utils
exiv2
expat
f3
fatresize
fd
ffmpeg
file
filesystem
findutils
firewalld
fish
flac
flashrom
flatpak
flatpak-kcm
fontconfig
frameworkintegration
freeglut
freerdp
freetype2
fribidi
fuse-common
fuse-overlayfs
fuse2
fuse3
fwupd
fwupd-efi
galileo-mura
gamemode
gamescope
gawk
gc
gcab
gcc-libs
gdb
gdb-common
gdbm
gdk-pixbuf2
geoclue
gettext
ghostscript
giflib
git
glew
glfw-x11
glib-networking
glib2
glibc
glibmm
glu
gmp
gnupg
gnutls
gobject-introspection-runtime
gperftools
gpgme
gpm
gptfdisk
gpu-trace
graphene
graphite
grep
grub
gsettings-desktop-schemas
gsm
gssproxy
gst-plugins-base
gst-plugins-base-libs
gstreamer
gtk-update-icon-cache
gtk3
gtkmm3
guile
gwenview
gzip
harfbuzz
hicolor-icon-theme
hidapi
highway
holo-desync
holo-dmi-rules
holo-fstab-repair
holo-keyring
holo-nix-offload
holo-sudo
htop
hunspell
hwdata
iana-etc
ibus
ibus-anthy
ibus-hangul
ibus-pinyin
ibus-table
ibus-table-cangjie-lite
icu
ijs
imath
iotop
iproute2
iptables
iputils
iso-codes
iw
iwd
jansson
jasper
jbig2dec
jq
json-c
json-glib
jupiter-dock-updater-bin
jupiter-fan-control
jupiter-firewall
jupiter-hw-support
jupiter-legacy-support
jupiter-resolved-nomdns
jupiter-steamos-log-submitter
kaccounts-integration
kactivities
kactivities-stats
kactivitymanagerd
karchive
kate
kauth
kbd
kbookmarks
kcmutils
kcodecs
kcolorpicker
kcompletion
kconfig
kconfigwidgets
kcontacts
kcoreaddons
kcrash
kdbusaddons
kde-cli-tools
kde-gtk-config
kdeclarative
kdeconnect
kdecoration
kded
kdelibs4support
kdeplasma-addons
kdesu
kdialog
kdnssd
kdsoap
kdsoap-ws-discovery-client
kdumpst
kemoticons
kexec-tools
keyutils
kfilemetadata
kgamma5
kglobalaccel
kguiaddons
kholidays
khotkeys
ki18n
kiconthemes
kidletime
kimageannotator
kinfocenter
kio
kio-extras
kio-fuse
kirigami-addons
kirigami2
kitemmodels
kitemviews
kitty-terminfo
kjobwidgets
kjs
kmenuedit
kmod
knewstuff
knotifications
knotifyconfig
konsole
kpackage
kparts
kpeople
kpeoplevcard
kpipewire
kpmcore
kpty
kquickcharts
krb5
krunner
kscreen
kscreenlocker
kservice
ksshaskpass
ksystemstats
ktexteditor
ktextwidgets
kunitconversion
kuserfeedback
kwallet
kwallet-pam
kwayland
kwayland-integration
kwidgetsaddons
kwin
kwindowsystem
kwrited
kxmlgui
l-smash
lame
layer-shell-qt
lcms2
ldb
ldns
less
lib32-alsa-lib
lib32-alsa-plugins
lib32-brotli
lib32-bzip2
lib32-curl
lib32-dbus
lib32-e2fsprogs
lib32-expat
lib32-flac
lib32-fontconfig
lib32-freetype2
lib32-gamemode
lib32-gamescope
lib32-gcc-libs
lib32-glib2
lib32-glibc
lib32-harfbuzz
lib32-icu
lib32-keyutils
lib32-krb5
lib32-libasyncns
lib32-libcap
lib32-libdrm
lib32-libelf
lib32-libffi
lib32-libgcrypt
lib32-libglvnd
lib32-libgpg-error
lib32-libidn2
lib32-libldap
lib32-libnm
lib32-libogg
lib32-libpciaccess
lib32-libpipewire
lib32-libpng
lib32-libpsl
lib32-libpulse
lib32-libsndfile
lib32-libssh2
lib32-libtasn1
lib32-libtirpc
lib32-libunistring
lib32-libunwind
lib32-libva
lib32-libva-mesa-driver
lib32-libvdpau
lib32-libvorbis
lib32-libx11
lib32-libxau
lib32-libxcb
lib32-libxcrypt
lib32-libxcrypt-compat
lib32-libxdamage
lib32-libxdmcp
lib32-libxext
lib32-libxfixes
lib32-libxi
lib32-libxinerama
lib32-libxml2
lib32-libxshmfence
lib32-libxss
lib32-libxtst
lib32-libxxf86vm
lib32-llvm-libs
lib32-lm_sensors
lib32-mangohud
lib32-mesa
lib32-mesa-vdpau
lib32-ncurses
lib32-nspr
lib32-nss
lib32-openal
lib32-openssl
lib32-opus
lib32-p11-kit
lib32-pam
lib32-pcre2
lib32-pipewire
lib32-renderdoc-minimal
lib32-sqlite
lib32-systemd
lib32-util-linux
lib32-vulkan-icd-loader
lib32-vulkan-radeon
lib32-wayland
lib32-xcb-util-keysyms
lib32-xz
lib32-zlib
lib32-zstd
libaccounts-glib
libaccounts-qt
libarchive
libass
libassuan
libasyncns
libatasmart
libavc1394
libblockdev
libbluray
libbpf
libbs2b
libbsd
libbytesize
libcanberra
libcap
libcap-ng
libcbor
libcec
libcloudproviders
libcolord
libcups
libdaemon
libdatrie
libdbusmenu-qt5
libdecor
libdmtx
libdrm
libedit
libelf
libepoxy
libevdev
libevent
libfakekey
libfdk-aac
libffi
libfontenc
libfreeaptx
libftdi
libgcrypt
libgirepository
libglvnd
libgpg-error
libgudev
libgusb
libhangul
libibus
libical
libice
libidn
libidn2
libiec61883
libimobiledevice
libinih
libinput
libjcat
libjpeg-turbo
libjxl
libkdcraw
libkexiv2
libksba
libkscreen
libksysguard
libldac
libldap
libmalcontent
libmbim
libmd
libmfx
libmm-glib
libmnl
libmodplug
libmtp
libndp
libnet
libnetfilter_conntrack
libnewt
libnfnetlink
libnftnl
libnghttp2
libnl
libnm
libnotify
libnsl
libogg
libomxil-bellagio
libopenmpt
libp11-kit
libpaper
libpcap
libpciaccess
libpgm
libplist
libpng
libproxy
libpsl
libpulse
libqaccessibilityclient
libqalculate
libqmi
libqrtr-glib
libraw
libraw1394
librsvg
libsamplerate
libsasl
libseccomp
libsecret
libsigc++
libslirp
libsm
libsmbios
libsndfile
libsodium
libsoup
libsoup3
libsoxr
libspectre
libssh
libssh2
libstemmer
libsysprof-capture
libtasn1
libteam
libthai
libtheora
libtiff
libtirpc
libtommath
libtool
libtraceevent
libtracefs
libunistring
libunwind
libusb
libusbmuxd
libutempter
libva
libva-intel-driver
libva-mesa-driver
libvdpau
libverto
libvorbis
libvpx
libwacom
libwbclient
libwebp
libx11
libxau
libxaw
libxcb
libxcomposite
libxcrypt
libxcrypt-compat
libxcursor
libxcvt
libxdamage
libxdmcp
libxext
libxfixes
libxfont2
libxft
libxi
libxinerama
libxkbcommon
libxkbcommon-x11
libxkbfile
libxml2
libxmlb
libxmu
libxpm
libxrandr
libxrender
libxres
libxshmfence
libxslt
libxss
libxt
libxtst
libxv
libxxf86vm
libyaml
libzip
licenses
lilv
linux-api-headers
linux-firmware-neptune
linux-firmware-neptune-whence
linux-neptune-61
llvm-libs
lm_sensors
lmdb
lsb-release
lsof
lua
luit
lv2
lz4
lzo
makedumpfile
maliit-framework
maliit-keyboard
mandoc
mangohud
md4c
mdadm
media-player-info
mesa
mesa-utils
mesa-vdpau
milou
minizip
mkinitcpio
mkinitcpio-busybox
mobile-broadband-provider-info
modemmanager
modemmanager-qt
mpfr
mpg123
mtdev
nano
ncdu
ncurses
netavark
nethogs
nettle
networkmanager
networkmanager-openvpn
networkmanager-qt
nfs-utils
nfsidmap
nftables
noise-suppression-for-voice
noto-fonts
noto-fonts-cjk
npth
nspr
nss
nss-mdns
ntfs-3g
numactl
nvme-cli
ocl-icd
okular
oniguruma
openal
opencore-amr
openexr
openjpeg2
openssh
openssl
openvpn
opus
orc
ostree
oxygen
oxygen-sounds
p11-kit
p7zip
p8-platform
pacman
pacman-mirrorlist
pam
pambase
pango
pangomm
parted
partitionmanager
paru
pavucontrol
pciutils
pcre
pcre2
pcsclite
perf
perl
perl-error
perl-mailtools
perl-timedate
phonon-qt5
phonon-qt5-gstreamer
pinentry
pipewire
pipewire-alsa
pipewire-audio
pipewire-jack
pipewire-pulse
pixman
pkcs11-helper
plasma-browser-integration
plasma-desktop
plasma-disks
plasma-firewall
plasma-framework
plasma-integration
plasma-meta
plasma-nm
plasma-pa
plasma-remotecontrollers
plasma-systemmonitor
plasma-thunderbolt
plasma-vault
plasma-wayland-protocols
plasma-wayland-session
plasma-welcome
plasma-workspace
plasma-workspace-wallpapers
podman
polkit
polkit-kde-agent
polkit-qt5
poppler
poppler-data
poppler-qt5
popt
portaudio
powerbuttond
powerdevil
powertop
ppp
prison
procps-ng
protobuf
protobuf-c
psmisc
pulseaudio-qt
purpose
python
python-aiohttp
python-aiosignal
python-anyio
python-async-timeout
python-attrs
python-capng
python-certifi
python-chardet
python-charset-normalizer
python-click
python-crcmod
python-dbus-next
python-distro
python-evdev
python-frozenlist
python-gobject
python-h11
python-hid
python-httpcore
python-httpx
python-idna
python-multidict
python-progressbar
python-protobuf
python-psutil
python-pyalsa
python-pyaml
python-pyelftools
python-pyenchant
python-pyinotify
python-semantic-version
python-sniffio
python-systemd
python-sysv_ipc
python-typing_extensions
python-utils
python-yaml
python-yarl
pyzy
qca-qt5
qqc2-desktop-style
qrencode
qt5-base
qt5-declarative
qt5-feedback
qt5-graphicaleffects
qt5-location
qt5-multimedia
qt5-quickcontrols
qt5-quickcontrols2
qt5-sensors
qt5-speech
qt5-svg
qt5-tools
qt5-translations
qt5-wayland
qt5-webchannel
qt5-webengine
qt5-webview
qt5-x11extras
rauc
rav1e
re2
readline
renderdoc-minimal
ripgrep
rpcbind
rsync
rtkit
rxvt-unicode-terminfo
sbc
sddm-kcm
sddm-wayland
sdl2
seatd
sed
serd
shadow
shared-mime-info
signon-kwallet-extension
signon-plugin-oauth2
signon-ui
signond
slang
slirp4netns
smartmontools
smbclient
snappy
socat
solid
sonnet
sord
sound-theme-freedesktop
source-highlight
spectacle
speex
speexdsp
sqlite
squashfs-tools
sratom
srt
sshfs
steam-im-modules
steam-jupiter-stable
steam_notif_daemon
steamdeck-dsp
steamdeck-kde-presets
steamos-atomupd-client-git
steamos-customizations-jupiter
steamos-devkit-service
steamos-efi
steamos-kdumpst-layer
steamos-log-submitter
steamos-reset
steamos-systemreport
steamos-tweak-mtu-probing
strace
sudo
svt-av1
syndication
syntax-highlighting
systemd
systemd-libs
systemd-swap
systemd-sysvcompat
systemsettings
taglib
talloc
tar
tcl
tdb
tevent
threadweaver
tk
tmux
tpm2-tss
trace-cmd
tracker3
tree
tslib
ttf-dejavu
ttf-hack
ttf-twemoji-default
tzdata
udisks2
unrar
unzip
upower
usbhid-gadget-passthru
usbutils
util-linux
util-linux-libs
v4l-utils
vid.stab
vim
vim-runtime
vkmark-git
vmaf
volume_key
vpower
vulkan-icd-loader
vulkan-radeon
vulkan-tools
wayland
wayland-utils
webrtc-audio-processing
wget
which
wireguard-tools
wireless-regdb
wireless_tools
wireplumber
wpa_supplicant
x264
x265
xbindkeys
xbitmaps
xcb-proto
xcb-util
xcb-util-cursor
xcb-util-errors
xcb-util-image
xcb-util-keysyms
xcb-util-renderutil
xcb-util-wm
xdg-dbus-proxy
xdg-desktop-portal
xdg-desktop-portal-kde
xdg-user-dirs
xdg-utils
xdotool
xf86-input-libinput
xf86-video-amdgpu
xkeyboard-config
xorg-fonts-encodings
xorg-server
xorg-server-common
xorg-setxkbmap
xorg-xauth
xorg-xdpyinfo
xorg-xhost
xorg-xkbcomp
xorg-xmessage
xorg-xprop
xorg-xrandr
xorg-xrdb
xorg-xset
xorg-xsetroot
xorg-xwayland-jupiter
xorg-xwininfo
xorgproto
xterm
xvidcore
xxhash
xz
yajl
zenity-light
zeromq
zimg
zip
zlib
zsh
zstd
zxing-cpp