(feature request) Provide more troubleshooting knowledge about failure to boot

[SemanticBeeng]

The article is of great use, thanks.

Applied within a Virtualbox VM to build a USB/microSD stick using EFI boot and native encryption options.
Now fails to boot : nativelly and within Virtualbox VM using vmdk rawfile to boot from usb.

Expected issues because disk names changed (between time of preparing the USB as VM attachment and the time of using as disks in another VM) but failure to boot does not give any error or hint to help troubleshoot.
Seems does not even reach grub in boot partition.

I am able to enter with Live CD and partitions look correct.
Can see the grub file...

It would be great to have details on how the boot workflow is supposed to work: find boot partition, activate GRUB, open the bpoo, look for rpool, etc.
Will continue to figure it out and advise if I succeed.

Thanks!