For those who own the game, here's a general guide to creating an ISO file:
To download Forza Horizon 5 PPSSPP ISO on your Android device, follow these steps: forza horizon 5 ppsspp iso download android mobile link
For the FH5 graphics to appear, move the "TEXTURES" folder into the Internal Storage > PSP > TEXTURES directory. For those who own the game, here's a