When you see a file labeled as a "GTA San Andreas PSP EBOOT.PBP," it falls into one of three categories:
Because the PSP has a built-in PS1 emulator (POPS), users often convert PS1 games into EBOOT.PBP files to play them on custom firmware. Since San Andreas was a PS2 game, it cannot be converted this way. How People "Play" San Andreas on PSP Today
If the game freezes on a black screen, ensure your CFW is active. You may need to change your ISO Driver in the VSH Menu (usually Select + Select) to "Sony NP9660" or "Inferno."
This is the standard file format for executable homebrew games, applications, and converted PlayStation 1 (PS1) games on the PSP.