The primary reason you might see downloads for a "Hitman 3 ISO" on PSP is due to title confusion or custom mods.
Websites or links claiming to offer a "Hitman 3 PPSSPP ISO" are often fake or contain different games (such as or Hitman: Absolution mobile ports) modified to look like Hitman 3. Playable Hitman Alternatives on Android Hitman 3 PPSSPP ISO File Download Android Isoroms