Thanks for highlighting these Stefan - you guessed correctly that I'd missed them on the review.

For your first question, I agree getawaitablefunc / aiternextfunc / getaiterfunc should all be dropped and replaced with the existing "unaryfunc".

For your second question, I agree it makes more sense for Coroutine to inherit from Awaitable than it does to have it registered with it.

For the other three, I don't have a strong opinion, except that we should make sure that whatever we do on the CPython side works by default for Cython.