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).
Very few people need it but it’s awesome and a lot of fun and lets you spend more time in Linux than dealing with Windows. The VFIO Reddit and Arch wiki are great resources. I have GPU, USB, and Ethernet pass through on my Ubuntu machine and it works great, but I needed the Arch wiki to really figure out what I was doing wrong when I first set it up. Level1Techs is also a good resource on YouTube and forums because they are big into VFIO and SR-IOV. Next time you get a PC, make sure to look for more PCI lanes and bifurcation support on your motherboard. Gen 4 is a great option because it generally has enough lanes and the ram and ssd are much cheaper than Gen 5. GPU choice doesnt matter much but if you’ve got AMD watch out for the reset bug. Basically you can start a VM but once you quit it the cards state is unavailable for further use (eg a second VM session or reopening your DE if you’re using a single GPU setup) unless you restart your host. There are some workarounds but personally I’d avoid it if possible. Onboard graphics (iris or amd APU) are recommended. Older hardware can get cheap so good luck saving up if this is something you want to do!