Currently all plugins need to be registered as a Python entrypoint.
Afaik entrypoints can only be registered via a setup script. If that doesn't fit in your workflow now, we could maybe add a command-line option or additionally support resolving plugins by their FQN additionally to the entrypoint name. Please do open a new issue in that case though :)
While this approch is occasionally seen in other projects, I personally view "using setup.py as a plugin/extension interface" to be a hack rather than an API.
From https://github.com/NiklasRosenstein/pydoc-markdown/issues/70#issuecomment-658705072:
While this approch is occasionally seen in other projects, I personally view "using
setup.py
as a plugin/extension interface" to be a hack rather than an API.