Incredibly, some PSP hackers have managed to load up Mac OS 7 on a PSP using an emulator called PSPbochs. The only downside is that it takes 4 hours to boot.
“Through a combination of PSPbochs (x86 emulator for PSP) and vMac (680×0 emulator for x86) – Mac OS 7 is running on a PSP! Since it’s an emulator running on an emulator running on a slow-ish processor, the whole thing takes about 4 hours to boot. But who cares?!”