A basic flake.nix file for cross-platform Python projects. Use with "nix develop". pip, etc. should work via venv.

flake.nix

{
  description = "A flake for pythonification";

  inputs = { 
    nixpkgs.url = "github:nixos/nixpkgs";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils, ... }@inputs:
  flake-utils.lib.eachSystem ["x86_64-darwin" "aarch64-darwin" "x86_64-linux" "aarch64-linux"] (system:
  let
    pkgs = import nixpkgs { inherit system; };

    pythonPackages = pkgs.python3Packages;

    venvDir = "./env";

    runPackages = with nixpkgs; [
      pythonPackages.python
      pythonPackages.venvShellHook
    ];

    devPackages = with nixpkgs; runPackages ++ [
      pythonPackages.pylint
      pythonPackages.flake8
      pythonPackages.black
    ];

    postShellHook = ''
      PYTHONPATH=\$PWD/\${venvDir}/\${pythonPackages.python.sitePackages}/:\$PYTHONPATH
    '';

  in {
    runShell = pkgs.mkShell {
      inherit venvDir;
      name = "pythonify-run";
      packages = runPackages;
      postShellHook = postShellHook;
    };
    devShells = {
      default = pkgs.mkShell {
        inherit venvDir;
        name = "pythonify-dev";
        packages = devPackages;
        postShellHook = postShellHook;
      };
    };
  });
}

If you copy this into an existing non-Nixified git-cloned python project, remember to "git add flake.nix" or it won't be "seen".

Also, may need to modify based on your particular requirements.

I haven't tried it yet on linux, but it works on macOS.

You access it/drop into its environment via nix develop.

I'm not 100% sure about the "runShell" definition. May need to modify this for runs and builds that are not "development", such as if you want any build products to be available on your PATH from elsewhere. (Happy to take recommendations here!)