Declaring Python packages in flake.nix

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Hi fellow people,

I was trying out different options managing python environments. For now I am using a flake based on GitHub - kemalmao19/devShell: Dev environment with flake.nix.

However I changed my flake so the python packages are not declared in packages = [ ] and rather in buildInputs = [ ].
This is because otherwise the lsp of helix editor would not work.
Here is my flake:

# 
# thanks to:
# https://github.com/kemalmao19/devShell/tree/main
# for inspiration
#

{
  description = "This is my python dev: Data Science Libraries Edition";

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

  outputs = { self, nixpkgs, }:
    let
      # Systems supported
      allSystems = [
        "x86_64-linux" # 64-bit Intel/AMD Linux
        "aarch64-linux" # 64-bit ARM Linux
        "x86_64-darwin" # 64-bit Intel macOS
        "aarch64-darwin" # 64-bit ARM macOS
      ];

      # Helper to provide system-specific attributes
      forAllSystems = f:
        nixpkgs.lib.genAttrs allSystems
        (system: f { pkgs = import nixpkgs { inherit system; }; });
    in {
      # Development environment output
      devShells = forAllSystems ({ pkgs }: {
        default = let
          # pint-pandas
          # Add units to pandas
          # This is fetched directly from pypi because version in nixpkgs is outdated
          pint-pandas = with pkgs.python311Packages; buildPythonPackage rec {
            pname = "Pint-Pandas";
            version = "0.5";
            format = "pyproject";
            src = fetchPypi {
              inherit pname version;
              sha256 = "SOyW1Ff4AqNHdj3uHT4aJz8R+Q5OWV3xf9RGE90Uphw=";
            };
            doCheck = false;
            nativeBuildInputs = [
              setuptools
              setuptools-scm
              wheel
            ];
            propagateBuildInputs = [
              pint
              pandas
            ];
          };

        in pkgs.mkShell {
          buildInputs = (with pkgs.python311Packages; [
            matplotlib
            toml
            pvlib
            pandas
            pint
          ]) ++ ([
            pint-pandas
          ]);
        };
      });
    };
}

And everything seems to work. Is there some danger in putting the python packages into buildInputs instead of packages?