I haven't followed this closely enough — if PEP 649 were accepted today, would it even be ready for use before the 3.10 code freeze (which is in a few weeks)?

Perhaps I'm a poor judge of the quality of my own code.   But I'd say I have a working prototype and it seems... fine.  It didn't require a lot of changes, it just needed the right changes in the right spots.  Getting my interactions with symtable and compile were the hardest parts and I think those are all sorted out now.

Cheers,

/arry