What I would like to see it's the full OS reimplementation a la AROS m68k.
There are Minivmac ports for 9front. Exegutor it's made in C++, so no way to compile it with NPE (micro-POSIX compat layer for 9front). If anyone had that under MiniVmac, it could run everywhere.
On Advanced Mac Substitute, as it has an SDL2 interface, it can be almost done unless it's written in C++. If it's ANSI C or C99, it might run under 9front.
Yes, I know about Ardi Executor being libre and enhanced now, but that's not the point.
I'd love to spawn MiniVMAC with a free system ROM replacement and a free Mac OS 7 reimplementation.