> While this works, I find this method a bit tedious to use, at least compared to Ventoy [0].

No, I find ventoy more tedious, because you can't use it as a standalone on your hard drive with a sane partitioning scheme.

The only reason is because of how the ventoy detection hardcodes the partition boundaries in its checks, and it means Ventoy can only run with the partitions set in a way that may lead to alignment issues like write-amplification: I've detailed that in https://github.com/ventoy/Ventoy/issues/1342

It used to be a warning - now it's a stopping error, causing the boot to hang. I don't like the boot to hang if the partition boundaries are changed.

Ideally I'd have a 10G partition after the EFI (or it could even be the EFI itself) with a few ISOs for rescue purposes + a UEFI entry to avoid having to use a bootable USB: automatically booting the ISOs in case the normal UEFI entry has a problem is less tedious that having to find and plug a thumbdrive.

I could give Ventoy its own partition wherever, but that's not possible unless I accept Ventoy hardcoded choices of partition boundaries:

                (pMBR->PartTbl[0].StartSectorId != 2048 ||
                    pMBR->PartTbl[1].SectorCount != 65536 ||
                    pMBR->PartTbl[1].StartSectorId != pMBR->PartTbl[0].StartSectorId + pMBR->PartTbl[0].SectorCount)

If you don't accept this, and want to boot of multiple ISO files by a grub2 bootloader, whether from a thumbdrive or a hard drive, also check the old https://github.com/a1ive/grub2-filemanager (now archived)