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).
If I could get vbox to work* on my laptop or find the drive to learn QEMU, then I would have plenty on there. For now I'm just stuck with plenty on my desktop running win10.
*I have installed it a few times on my Debian based distro, but I swear every time I do nothing to it and it destroys itself. Works fine one day, then the next I turn on my laptop, after the only changes being that I created and ran a VM and it decided to hate me and not even boot the program. I think I'm just cursed.
What about Virt Manager GUI, which is what I use here? It's a frontend for QEMU and it's not that difficult, honestly.
I'll have to look into it because I'd love to have some VMs on my laptop since it way outperforms my desktop specs wise