If your goal is to play the authentic, full version of GTA: San Andreas for free on a portable device, you should pivot away from the PSP hardware entirely.
This is the closest official game to San Andreas on the PSP. It features swimming, empire-building mechanics, bicycles, helicopters, and a massive licensed 1980s soundtrack. GTA: Liberty City Stories
If your goal is to play the authentic, full version of GTA: San Andreas for free on a portable device, you should pivot away from the PSP hardware entirely.
This is the closest official game to San Andreas on the PSP. It features swimming, empire-building mechanics, bicycles, helicopters, and a massive licensed 1980s soundtrack. GTA: Liberty City Stories how to play gta san andreas on psp free