Half of these exist because I was bored once.
The Windows 10 and MacOS ones are GPU passthrough enabled and what I occasionally use if I have to use a Windows or Mac application. Windows 7 is also GPU enabled, but is more a nostalgia thing than anything.
I think my PopOS VM was originally installed for fun, but I used it along with my Arch Linux, Debian 12 and Testing (I run Testing on host, but I wanted a fresh environment and was too lazy to spin up a Docker or chroot), Ubuntu 23.10 and Fedora to test various software builds and bugs, as I don't like touching normal Ubuntu unless I must.
The Windows Server 2022 one is one I recently spun up to mess with Windows Docker Containers (I have to port an app to Windows, and was looking at that for CI). That all become moot when I found out Github's CI doesn't support Windows Docker containers despite supporting Windows runners (The organization I'm doing it for uses Github, so I have to use it).
Not op but I do a lot of architecture and infrastructure work on top of my normal dev work so keeping everything separated and per-client has become a pretty important advantage for me personally
Yeah I also consult with many different clients. Sometimes those clients need me to install sketch software. Thank god I can do this in a silo in Qubes, or it could endanger my other clients.
Yep that I imagine is one of the main intended use cases, in my case would probably be overkill though