Hi,

This is a particularly AWFUL user experience bug. Installing GUIX to a
partition only lists GUIX in the grub boot menu afterward despite the
existence of other bootable OSes on the drive.

Ok fine thinks I, I will just need to manually run grub's mkconfig to force
re-detection. But this command does not exist in GUIX. Installing grub did
not create grub2-mkconfig. Installing osprober wasn't helpful.

I did not see documentation on how to make GUIX detect and add other
operating systems to the boot menu from userland. After much time wasted, I
needed to download another distro, install it so it would repair the boot
menu, and then be able to boot into my main partition.

Recommendation:
Installer needs to detect and add to the menu the other OSes.
Documentation needs to show how to do it manually via a different method if
GUIX does not include grub2-mkconfig otherwise it needs to warn upfront
that this distro should not be used on multi-boot PCs.

Best,
Peter