Such macros would make the code cleaner. But I don't think it should be provided as a part of API. It isn't hard to implement, it doesn't provide essential functionality of Python, and it doesn't hide implementation defined CPython internals. I rather consider it as private helper, so it should be declared with underscore prefix and inside the #ifndef Py_LIMITED_API/#endif block.

I don't see an implementation of Py_RICHCOMPARE. In any case I think it would be better to make the op parameter the first parameter.