I created a template which to the extent that I used it completly replaces the need for virtualenv and integrates well with declarative setuptools: https://github.com/takeda/example_python_project
With direnv + lorri when you enter the directory, it is as if you enter virtualenv, your code behaves as if it is installed with pip -e, if you call nix build it takes care of all dependencies and the command created in bin/ behave like binaries, have all dependencies needed.
I plan to update nixpkgs code that processes setup.cfg and make this less trivial example when I find some time.
