My personal recipe (on NixOS) is pip-ed virtual environment for quick tests, or conda inside a nix-shell, on top of a dedicated zfs pool/conda mounted in ~/.conda with dedup=on so nothing nixified and nothing that last a nixos-rebuild...

Many pythonic projects not only in ML world tend to be just developers experiments, so to be run as an experiment, not worth to be packaged as a stable, released program...

Oh, BTW projects like home-assistant fell in the same bucket...