Yea nix is an interesting angle of approach. It rhymes a lot with Bazel (reproducibility, explicit/declarative dependency tree, etc.), but nix approaches the problem from a different, lower layer of abstraction (by replacing the OS-level "pip" in apt, pacman, snap, brew, and the like).

I think, in the long run, something like nix will win out. It makes sense for your OS "package build system" to be the same as your project build system.

If your python project depends on some mildly obscure python lib, do you write your own nix "package" (or whatever nix chooses to call them) wrappers for each release you end up using? Any other tripwires in your experience so far?