Ventoy allows you to create a bootable USB containing any number of ISO files just by writing to a partition. It even supports Windows, and has some cool features like overriding Secure Boot on some machines.
You'll still have to go through basically the same excercise of the article if you want to boot another dist/iso than the ones it already recognizes.
There should be a way to automatize that, using Ventoy as a "database" of the recognized isos which could be fed to glim or anything else
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)
Compared to that, I think formatting another partition to install ventoy to (in the use case you're outlining), or updating a grub config with code like `loopback loop (hd0,5)`.. for me, these take more effort and care.
Though, I'll keep the posted solution in mind if I'm ever wanting to boot from ISOs and I happen to not have a spare thumb drive around.
The other partition with the ISOs is not for when I plan to boot into a newer live ISO (which I would have to add to the partition etc): it's for when I don't plan to, or even want to!!
The last time it helped me, I had made a configuration mistake on my laptop in an airport. "grab a spare thumbdrive, and install ventoy to that" would have been very painful, but rebooting and selecting from the UEFI grub2fm to then pick an ISO from which I could fix my mistakes was very easy (or at least, easier than the alternative!)
However TBH I I hadn't had such a setup, I don't think I'd have taken the risk of doing some configuration and UKI tweaks at the airport while bored :)
When booting the Windows ISO, the boot process would never progress past the screen showing the blue windows icon on a black background.