While maybe not impossible, it is quite hard to cox Nix to "install" multiple different versions of the packages. They all cannot be in your path at the same time.

I still encourage you to give it a try. You can build different versions of same package and not "install" them. Instead just execute the binary from the built version (I do this where I have a built-but-not-installed version of openssh-8.6 laying around because I have an old service that modern SSH no longer supports).

You can also run `nix-shell -p <custom-package-version>` to get a shell with a specific package available in the path, overtop of whatever might be globally installed.

Who knows, you might even be tempted to dip your toes into the Nix language by writing a custom `shell.nix` to build a shell with some more complex development environment, or to simply automate a complex `nix-shell -p` command.