Websites claiming to offer a "Mario Kart 8 Deluxe PSP ISO" are likely scams or contain malware. "Mario Kart PSP" Homebrew: There is an old fan-made project called Mario Kart PSP
Even with extreme optimization, the PSP lacks the shaders, processing power, and memory bandwidth required to render the gravity-defying tracks and high-definition assets of the modern Mario Kart experience. Ecosystem and Exclusivity
and was never officially released or ported to Sony hardware.
Advanced users use third-party software like to stream real-time video from a PC or a jailbroken console to the PSP screen.