It seems that nix supports spacy, along with its models, in version 3.4.7 that we currently use:

https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/python-modules/spacy/models.json

Maybe it's better to use it to set up spacy, even if in the end we wanted to build a Docker image (though I'm not sure it's needed here, because we don't keep any data in spacy, we just have a simple, stateless API server here to use the spacy lib). Most of the bookkeeping is about downloading models and running servers for a proper model.