Booting the *buntu focal fossa isos (I've tried Ubuntu, Kubuntu and Lubuntu), after renaming the isos to match the scripts in mbusb.d, gives a busybox error during the boot:

`No loop devices available: no such file`

and one gets an initramfs prompt. I'm not sure this is a problem that multibootusb can fix, but I don't know, maybe it can be fixed with an adjustment to the script.

I stumbled on a workaround:

1. Press control-d; one gets a different busybox error, that suggests the next step...
2. Run
   mount -o loop /cdrom/casper/filesystem.squashfs /filesystem.squashfs
3. Press control-d again.