I'd genuinely be curious what fraction of those changes actually requires porting to other Python implementations. The free-threading changes are inherently interpreter specific, so we can ignore those. A significant change in Python 3.12 is dropping "dead batteries", so that can be ignored as well. From what I can see, the main language changes are typing-based (so could have parser implications), and the subinterpreter support being exposed at the Python level (I don't know whether that makes sense for PyPy either). I think this hints that while certain area of Python are undergoing larger changes (e.g. typing, free-threading), there is no obvious missing piece that might drive someone to contribute to PyPy.

Also, looking at the alternate (full) interpreters that have been around a while, PyPy is much more active than either Jython or IronPython. Rust-python seems more active than PyPy, but it's not clear how complete it is (and has going through similar periods of low activity).

Would I personally use PyPy? I'm not planning to, but given how uv is positioning itself, this gives me vibes of youtube stating it will drop IE 6 at some unspecified time in order to kill IE 6 (see https://benjamintseng.com/2024/02/the-ie6-youtube-conspiracy...).