PyPy wasn't great for me because its startup time interfered with the main usecase I wanted it for in one instance and in another there bugs that made it not quite compatible enough. Money could solve the bug issue.
On the other hand I did get pygame working with it at one point and that seemed like a nice scenario.
And all of them are lacking in different ways, we ALSO, want faster pure Python.
Pypy does provide faster pure Python. Its a compatible implementation with JIT.
And from what I understand there are limitations with using libraries that use the CPython API to interface with native code.