I'm a little confused about why you need Unity to launch a web view in full screen. It's been a minute since I've written an Android app, but isn't this like... less than a hundred lines of Java?
Not "they". He. I'm only person. And yes, I use Unity because it's cross platform. Well, at least it was cross platform, until they closed my Google Play Developer account 2 days ago :-(
It was a stupid experiment. A useless app I shoud have unpublished years ago. I used Unity because I'm familiar with Unity and didn't want to deal with Android Studio and native development stuff.
