Can someone with a bit more chip-level knowledge explain to me why nobody has put a PiStorm into a classic Mac yet?

https://github.com/captain-amygdala/pistorm

If there are problems with the ISA or something, they're much much easier to tweak here. It already works in multiple models of Amiga, including both 68000 and 68020, and there's at least one effort to get one working in an Atari ST...

someone did https://tinkerdifferent.com/threads/pistorm-on-the-macintosh...

personally I think it's a bit too close to just emulating the whole thing

I didn't know about that! :-o Thanks!

> personally I think it's a bit too close to just emulating the whole thing

Yes, I do know what you mean.

Although it's functionally more limited, there is also Emu68, which removes the native PiOS from the setup completely.

https://github.com/michalsc/Emu68