I see, and it's a pretty short list:

https://doc.pypy.org/en/latest/cpython_differences.html#exte...

""" The extension modules (i.e. modules written in C, in the standard CPython) that are neither mentioned above nor in lib_pypy/ are not available in PyPy. """

The lifecycle of generators makes pypy code very verbose without refcounting. I've already been bitten with generator lifecycles and shared resources. PEP533 to fix this was deferred. Probably for the best as it seems a bit heavy-handed.