There is no official God of War Ragnarök file for the PSP , as the game was never released for that console. The game is officially available only on PlayStation 5 PlayStation 4 Windows (PC) God of War Wiki

The PSP hosts two of the most critically acclaimed titles in the series. If you are looking for an authentic handheld Kratos experience, these are the files you should seek: God of War: Chains of Olympus (2008)

If you're still interested in downloading a PSP file for God of War Ragnarok, here are some websites that claim to offer PSP game downloads: