This is not an issue but rather information/documentation how I added the fantastic-packages which might help other

[diepeterpan]

Alternate semi-manual method:

1. Add the following to /etc/opkg/customfeeds.conf, can be done via Luci System / Software / Configure opkg

Change 23.05 and aarch64_cortex-a53 where necessary for your router's chipset architecture

src/gz fantastic_packages_packages https://fantastic-packages.github.io/packages/releases/23.05/packages/aarch64_cortex-a53/packages
src/gz fantastic_packages_luci https://fantastic-packages.github.io/packages/releases/23.05/packages/aarch64_cortex-a53/luci
src/gz fantastic_packages_special https://fantastic-packages.github.io/packages/releases/23.05/packages/aarch64_cortex-a53/special

2. In a command line on the router install the certificate to verify the packages

Change 23.05 and 53ff2b6672243d28 where necessary for your router's

cd /tmp
wget https://fantastic-packages.github.io/packages/releases/23.05/53ff2b6672243d28.pub
opkg-key add 53ff2b6672243d28.pub

3. Update lists in Luci System / Software

4. Select and install Fantastic Packages via Luci

[R0iZ]

There is an error during opkg update:
Downloading /Packages.gz Failed to allocate uclient context *** Failed to download the package list from /Packages.gz