A year or two ago I built dropbear on Power MachTen, worked great and just needed a couple fixes to bring it back into compatibility with GCC 2.x.

Playing around with Professional MachTen (for 68k) is a real trip though. 4.3BSD, an even older GCC, and it implements virtual memory and protection by taking over the system memory manager. (You actually have to restart when quitting it)

It would be so cool to have something like MachTen on iOS, some people have tried but the restrictions on executable pages really restricts things.