When using sphinx\'s automodule (https://www.sphinx-doc.org/en/master/usage/extensions/autodoc.html),
I simply write in a .rst file:
.. automodule:: my_m
It seems to me that using the :imported-members: option (non-direct link, do use search) should now be possible, if __init__.py imports those submodules.
__init__.py
However, I'm personally not able to make this work (yet).
EDIT: Possibly a known bug.