Since there is no official PSP version, the "GTA San Andreas PPSSPP" experience is actually achieved through . Developers take existing PSP GTA titles and modify their textures, maps, and characters to resemble San Andreas. Exploring GTA San Andreas on PPSSPP - AliExpress
: While tools like KGB Archiver can drastically shrink files, compressing a multi-gigabyte game to 15 MB would result in a broken, unplayable file.
A standard installation of GTA San Andreas on mobile or PC typically requires of storage. Claims of a 15 MB "highly compressed" version are almost always misleading.