Consider a module like

foo/
    __init__.py
    __init__.pyi
    bar.py
    baz.py

Where __init__.py is

import lazy_loader as lazy

# this assumes there is a `.pyi` file adjacent to this module
__getattr__, __dir__, __all__ = lazy.attach_stub(__name__, __file__)

__init__.pyi is

from .bar import *
from .baz import *

https://typing.readthedocs.io/en/latest/source/stubs.html#imports says that * imports are re-exported. Therefore lazy.attach_stub should resolve the star imports from bar.py and baz.py. Instead foo.__all__ == [*].