Since autoapi doesn't import files, in theory it shouldn't need to be installed in the project venv, which would be ideal(To prevent the risk of a package conflict, more isolation is usually better!), but this seems to result in a lot of autoapi.python_import_resolution errors if you try to document just one submodule that represents the public API.
Currently my workaround is just to build the docs for the whole project, even if only a small part represents the stable API.