My two cents, but I'm not sure how possible that'd actually be. Yeah, you can absolutely still make PSP games nowadays, but despite the retro look, this game was made in the Unreal Engine.
Modern Unreal games are basically guaranteed to run poorly on PSP even if you did somehow manage a port, and it was never officially supported.
Your best bet would either be finding someone who has already figured out how to port Unreal games to PSP, or doing the hard work yourself.