Android Virtual Camera Loop Stealth

I need a dependable way to feed an Android device (I work with a Samsung S10+ image) a looping MP4 so every app that opens the rear camera sees a continuous “live” stream. The approach must run entirely on the phone or its emulator layer; using desktop software such as OBS is off the table... (Budget: $250 - $750 USD, Jobs: Android, Android App Development, Android SDK, Android Studio, Java, Linux, Mobile App Development, Video Processing)