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,