I created Tiny Flashlight for Android 12 years ago. It's been downloaded almost 500m times. Back then every hardware vendor implemented the camera API in their own way and it wasn't easy to start the camera led. I had to purchase many different devices from different carriers from all around the world just to find out a way to start the camera LED. It was very helpful when the vendor published the kernel source code with the camera drivers for the particular device model. I could send custom commands to the driver to start the LED, where it was not possible using the standard camera API.
I used Goodle Admob (back in the day it was only Admob) to monetize it. Thanks to the monetization I managed to purchase all of these devices and develop the app further. It was like finding a way to solve a tiny bootstrapping problem.
