`download` script requires pip
I use uv without pip, so I get the following:
(venv) PS C:\Users\me\> python -m spacy download en_core_web_sm
C:\Users\me\.venv\Scripts\python.exe: No module named pip
I don't think you need a script to call pip for users.
If your models are all pip-installable packages, they should depend on their supported versions of spacy. Then the user's dependency resolver can find the correct model version to download.
for uv users, uv pip install pip
currently a side-effect of this limitation is that it forces users of package managers other than pip to have to use two in their project... uv said it's spaCy-specific design and they will not adapt to it (https://github.com/astral-sh/uv/issues/7327#issuecomment-3352652323). do you plan on introducing support for uv / poetry users (without mandatory pip installation)?
spaCy can also just add pip as a dependency, if you want to continue with this approach. You shouldn't assume pip is installed otherwise though.