In case anyone else is similarly curious, I managed to get the ubuntu images to build .qcow2 images with some lightweight patches to the packer files and the interior .sh provisioning scripts. I have intention of setting up (heh) GHA to build them on the regular but it has not yet risen to be the highest priority weekend project

If you may say "but, why?!" it's because I really wanted to know what versions of everything I could expect in GHA, and I detest "git commit -amdummy && git push" stupidity so I guess the answer is "because I'm wired that way"