This is something that's up to the community really. The PyPy developers early on made a new FFI that is also available for CPython, sadly not entirely as easy as the classic API but completely functional and if there was a push to rewrite extensions to use that FFI (or provide dual-paths) then the gap could be bridged.
They didn't update their website often , that is the main problem of people not knowing much about PyPy . But they had made CPyext compatible and works fine with several Data-science Libs over past 2-3 years . Even anaconda have a miniconda for pypy called pypyforge where many of CPyext are building fine with it and they have same performance comapre to CPython. ( Can't make C-Extension faster since they are already C anyways.)