If you create a Multi-Disk image with a dual boot configuration, the efi boot entries will not be maintained automatically when deployed to different hardware
To Fix this you should create a post-install script to handle it
See also https://forums.fogproject.org/topic/16703/dual-boot-2-disks-unable-to-boot-grub
Post install scripts can be added on the fog server at /images/post-install
You need to use efibootmgr in a post script to configure the efi boot entries and maintain your dual boot config
` efibootmgr -c -d /dev/nvme0n1 -p 1 -L "Debian" -l "\EFI\debian\shimx64.efi"`