Installing a custom python package into a nix development env

Hello,

We want to install a home-made python package xyz into the nix development environment using the flake.nix file, so when I run `ǹix develop``, it creates a shell with the right python, artiq, and our custom package. This is installed using pip and setup.py file at the moment.

We are migrating away from conda, and at the moment, the experiment files import modules from xyz directly. I prefer to not change the experiment files.

How can I do this? Here is my file system structure, and the contents of flake.nix file:

./
|---- flake.nix
|---- flake.lock
|---- local_packages/
|     |---- xyz/
|     |     |---- setup.py
|     |     |---- build stuff	
|---- repository/
|     |---- experiment files

flake.nix

{
  inputs = {
    artiq.url = "git+https://github.com/m-labs/artiq.git?ref=release-8";
    artiq-comtools.follows = "artiq/artiq-comtools";
    artiq-extrapkg = {
      url = "git+https://git.m-labs.hk/M-Labs/artiq-extrapkg.git?ref=release-8";
      inputs.artiq.follows = "artiq";
    };
    nixpkgs.follows = "artiq/nixpkgs";
  };

  outputs = { self, artiq, artiq-comtools, artiq-extrapkg, nixpkgs }:
    let
      pkgs = import nixpkgs { system = "x86_64-linux"; };
      # Combine attribute sets for convenience
      artiq-full = artiq.packages.x86_64-linux // artiq-comtools.packages.x86_64-linux // artiq-extrapkg.packages.x86_64-linux;
    in
    {
      # Default shell for `nix develop`
      devShells.x86_64-linux.default = pkgs.mkShell {
        buildInputs = [
          # Python packages
          (pkgs.python312.withPackages (ps: [

            ps.redis
            ps.numpy
            ps.scipy
            ps.matplotlib
            ps.pyserial
            ps.colorlog         
          
            # From the artiq flake
            artiq-full.artiq

            # Additional packages
            artiq-full.artiq-comtools
            #ps.paramiko # needed for flashing boards remotely (artiq_flash -H)
          ]))
          # Non-Python packages
          #artiq-full.openocd-bscanspi # needed for flashing boards, also provides proxy bitstreams
          pkgs.git
        ];
      };
      # Enables use of `nix fmt`
      formatter.x86_64-linux = pkgs.nixpkgs-fmt;
    };

  # Settings to enable substitution from the M-Labs servers (avoiding local builds)
  nixConfig = {
    extra-trusted-public-keys = [
      "nixbld.m-labs.hk-1:5aSRVA5b320xbNvu30tqxVPXpld73bhtOeH6uAjRyHc="
    ];
    extra-substituters = [ "https://nixbld.m-labs.hk" ];
  };
}

How should I modify the flake file to do this?
Any help is appreciated!! (:

Clear skies,
Santhosh