I've tried multiple times to use PyPy on real projects and it was totally unusable if you rely on stuff like pandas, sklearn, keras, fastapi, etc. I found simil

I've tried multiple times to use PyPy on real projects and it was totally unusable if you rely on stuff like pandas, sklearn, keras, fastapi, etc. I found similar issues with Numba as well. These things only work if you keep to a relatively small subset of Python and stick to "pure python" functions. Which basically no one does (that I can see) except in toy projects and tutorials. Improving cpython by 1% (without breaking compatibility, which python 3.10+ did a poor job of in my view) would do more for the world than making PyPy even faster.