[zaarn]

That's pretty much your limitation; your linux kernel + initramfs can't be on filesystems other than VFAT (ie, must be on the ESP but there is some ways you can have it work across disks).

Hence the table being slightly misleading.

For example, it also mentions that EFISTUB means you can't boot on btrfs and friends anymore. But it's the same limitation, initramfs and kernel need to be on the ESP, everything after that is up to the initramfs to bring up.