Hello, what is a good, modern way to create and easily manage multiple virtual machines with different distributions on NixOS?
For example one completely isolated environment for Debian, one for ArchLinux, and so on…
I do not know if this is possible, but it would be very cool to have the vms declaratively set up, somewhere in my configuration.
Thank you in advance! 
There’s none to the best of my knowledge except for things like distrobox which are not declarative or integrated in NixOS.
It would be awesome if someone wrote a tool to declaratively manage them and also have it well integrated in NixOS. I am not sure how hard that would be though.
For “normal” distros stuff like Vagrant and Ansible is probably the easiest way to go.
However they don’t really integrate with NixOS.
Then we really need a tool for NixOS 
There is a tool by Martin Wimpress named quickemu (which has a release in nixpkgs) that allows for imperative command-line installation of various distros (see GitHub - quickemu-project/quickemu: Quickly create and run optimised Windows, macOS and Linux desktop virtual machines.)
Martin apparently just started to work for Determinate Systems, so I wouldn’t be suprised if quickemu got some nix integration eventually.
Uh nice, since it got quite some features since I last used it.
At the beginning you had to provide the ISOs manually.