Install packages with both virtualenv and python3.withPackages

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I want to have some packages installed with virtualenv (custom packages) and some I would like to have automatically installed, eg in withPackages. How can I obtain this? If I install numpy using pip install numpy, and then run python, I am able to import numpy, but not import torch. How can I fix this:

flake.nix:

{
  description = "A Python project with NumPy";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-22.11";
  };

  outputs = { self, nixpkgs }:
    let
      system = "x86_64-linux";
      pkgs = nixpkgs.legacyPackages.${system};
      pyEnv = pkgs.python3.withPackages (ps: with ps; [
        torch
        virtualenv
      ]);
      buildInputs = with pkgs; [
        pyEnv
        zlib
      ];
    in
    {
      devShell.${system} = pkgs.mkShell {
        buildInputs = buildInputs;
        shellHook = ''
          export LD_LIBRARY_PATH="${pkgs.lib.makeLibraryPath buildInputs}:$LD_LIBRARY_PATH"
          export LD_LIBRARY_PATH="${pkgs.stdenv.cc.cc.lib.outPath}/lib:$LD_LIBRARY_PATH"
          source venv/bin/activate
        '';
      };
    };
}