There can be various reasons why cheats might work on PPSSPP but not on a physical PSP. Here are a few possible explanations:
Cheat compatibility: Cheats created for PPSSPP might not be compatible with the specific PSP firmware version or hardware. The PSP may have different firmware or...
i gotta say, the steam deck isn't a bad deal, even if you get a used one, you have options to get it serviced and the parts are also available through ifixit