HowTo: Multi-boot isos/frugals/full via Ventoy
Been lots of multi-boot solutions posted and some close but somewhat messy attempts using Ventoy usb stick alone (since it comes with pre-installed grub2).
What seems to have been missed is the official Ventoy method that allows for any grub boot stanzas so works with frugal installs too, and isos that otherwise don't boot with usual Ventoy mechanism or don't successfully provide save persistence.
Details were discussed (with example) here: viewtopic.php?p=100455#p100455