You're looking for a Resident Evil 4 PPSSPP Android ISO file download that's highly compressed! Here are some useful resources and information that might help:
The PSP version is graphically inferior to the GameCube/Wii versions—textures are muddier, and some environmental details are missing. However, on a 5-6 inch smartphone screen, it looks perfectly acceptable and runs at full speed even on mid-range Android devices. You're looking for a Resident Evil 4 PPSSPP