https://www.nixhub.io/ - and I’ve seen others - make the searching easy. It’s odd to me that I rely so much on web based tools (like search.nixos.org!) to look up nixpkgs details for my commandline but eh.

For a flake, you’d specify an input of that specific revision of nixpkgs and then refer to your CMake dependency with respect to that input. You may end up with - by design - a lot of duplicated dependencies, but it’d work.

https://blog.mplanchard.com/posts/installing-a-specific-vers... is a nice writeup (not mine) with examples of a few different ways to do this in flakes and not-flakes.