...although python 3.13 can be built without the GIL and it really does make threading useful. I did some comparisons with and without.

I suppose one excellent thing about this would be if you could just change 1 parameter and switch from multiprocessing to threaded.

I think you could build off of threading. I do think here it's good to acknowledge that Python async is fundamentally single-threaded (or rather, "single thread per event loop"), so if you do go a multi-thread version you might have to do some bookkeeping to make it all work well.

I'm not sure how well async Python libs are tested against working in a world with multiple event loops, but I bet there are a _lot_ of latent bugs in that space.