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...).
The problem is the million small paper cuts. The stdlib changes are not all in pure python, many have implications for compiled modules like _ssl. The interpreter changes, especially compatibility with small interpreter changes that are reflected in the dis module, also require work to figure out
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...).