Tracking screen time in android

Question

I need to monitor an android smartphone's screen time for a school project. Finding accurate search results can be challenging because my search engines only recommend apps that already do this function for you. I'm curious how these apps accomplish this. I suppose there is a native Android API that helps you with this. Sadly, I can't locate anything that does this already.

The programme is designed to operate a small service that monitors screen activity and other things (like location). It would be wonderful if one of you could point me in the direction of examples and resources for the Android API.