Are there any PEPs that describe this work?
See the stable ABI for Python 3.15 and PEP 793, 803, 820 for recent movements in this general direction and the following draft: https://github.com/py-ni/peps/blob/main/peps/pep-08xx.rst (the py-ni project is pushing for this)
They reference this one in the article https://peps.python.org/pep-0836/