Can you install ANY OS on your ps2 p21 or psp?
PSPs which are able to run homebrew could use a port of "BOCHS"
to run basic operating systems on them. However a PSP is far too
slow to run any operating systems at useable speeds. PS2s can run
linux, if you buy one of the old kits and a USB keyboard, but again
it would be slow. PS3s could do this much faster, a Google for
"linux on PS3" would help you.