Yep, Nixpkgs freely relies on that kind of vendorization to solve compatibility problems in other programming languages' ecosystems when it has to. And Nix use

Yep, Nixpkgs freely relies on that kind of vendorization to solve compatibility problems in other programming languages' ecosystems when it has to. And Nix users can totally override specific Python library versions as one-offs for their own Python packages or environments. It's just really unfortunate that some of Python's internals make that unfeasible for Nixpkgs' collection of Python libraries as a whole. :(