I would personally suggest a more permanent and accessible way, in the way the decimal module handles it. I'd add a '_pycollections' module holding the pure Python implementations of OrderedDict and _count_elements, then have the collections package import them if the C accelerators don't work.

While the '_pydecimal' module is not guaranteed to remain across versions, successfully importing it means that you are guaranteed to use the pure Python version of it. In the same direction, successfully importing OrderedDict from _pycollections would guarantee that you're using the pure Python version of it.

This would have the side-effect of allowing people relying on the pure Python implementation details to use them (see #25315).