It looks like some of the optimizations in py_panda.* makes some assumptions about some Python structures that don’t work with PyPy. Perhaps we could use #ifdef to detect whether PyPy is used and fall back to a different approach for PyPy.
We did use python-config in the past, but abandoned it when it caused serious problems for the Panda build. One of the problems was that it included flags like -DNDEBUG that we absolutely didn’t want to inherit from the Python build.
As for the ABI tag, makewheel.py uses get_config_var(‘SOABI’) to determine the proper ABI tag. What is this set to for your PyPy installation?