– If you own a legal copy of Resident Evil 4 for PSP (e.g., UMD or digital PSP version), you can dump the ISO yourself using a PSP console or certain PC tools. That ISO can then be played on PPSSPP for Android.
Resident Evil 4 was never officially released for the PlayStation Portable (PSP)
With modern PC emulators for Android, you can actually run the 2005 PC version or even the Remake if you have a flagship device.
Genuine highly compressed files for complex 3D games usually range from 500MB to 1.5GB . Anything listed as "70MB" for a full game is likely a partial mod or potentially unsafe.