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).
I have about that many. Looks good to me! I have two Windows VMs. One for work and presentations. One for games and Adobe. A bunch of random Linux VMs trying to get a FireWire card to work and a Windows 7 VM for the same reason. I’ve also for several Linux VMs trying out new versions of Fedora, Ubuntu, or Debian. A couple servers. Almost none of them are ever turned on because my real virtualized workloads run in docker or LXC! I never could get Mac VM to work but I have an AMD CPU and a MacBook so not too high priority.
Screen sharing from Linux is amusing though, so far I've yet to have anyone even mention it (hyprland so looks very different to Windows