Most "PSP ISO" searches actually lead to the highly successful Hollow Knight PS Vita Port by developer PatnosDD. This is a functional, high-quality port that requires a modded Vita and legitimate game files from Steam or GOG.

The is a phantom. It does not exist as a native, playable, full-length game. The “Extra Quality” tag is a lure used by malware distributors and SEO clickbait farmers. No amount of custom firmware, overclocking, or compression magic will make Team Cherry’s masterpiece run on a 333 MHz MIPS processor with 64 MB of RAM.

If you ignore this advice and search the web anyway, here is how to avoid viruses:

Hollow Knight is set in the fictional world of Hallownest, a mysterious and ancient kingdom hidden beneath the earth. Players control a silent, hooded figure known as the Knight, who explores the vast, interconnected underground world, battling challenging enemies and uncovering hidden secrets.

There is no “Extra Quality” Hollow Knight on PSP. The keyword is SEO spam used by shady ad-supported download sites.

The game's visual storytelling is another key element in crafting its atmosphere. The world of Hallownest is a twisted, nightmarish realm, filled with grotesque creatures and haunting landscapes. The game's art style, a blend of dark fantasy and Victorian-era aesthetics, is both beautiful and unsettling.

The game features:

For a high-quality, full-game experience on a PlayStation handheld, the community focus is almost entirely on the PS Vita homebrew port