Files found on sites like isoroms.com claiming to be "ETS2 for PPSSPP" are usually modified versions of other PSP games (such as Hard Truck: Apocalypse or 18 Wheels of Steel mods) or potentially unsafe files. Authentic Ways to Play ETS2 on Android
If you want to play the real Euro Truck Simulator 2 on your Android device, you must use streaming or emulation of the PC version: Files found on sites like isoroms
That being said, I found a few sources that offer Euro Truck Simulator 2 and PPSSPP APK downloads: Understanding Mobile "Downloads"
PPSSPP Android APK download, there is currently of the game for the PSP or Android platforms . Euro Truck Simulator 2 (ETS2), developed by SCS Software , is strictly a desktop experience supported on Windows, macOS, and Linux . Understanding Mobile "Downloads" developed by SCS Software