In my dealings with React Native, I have found certain plugins disappointing, so I am considering writing my own plugin in Kotlin. Obviously, that requires knowledge of Kotlin and how to develop for Android. I know the barest basics of Kotlin, but I know of a few resources to improve my knowledge of the language.

What I'd like to ask from you guys is if you know of any good tutorial, book, playground or other such things to learn Kotlin specifically to develop Android apps.

Bonus points if you can also point me to somewhere that explains how to develop plugins for React Native.

Thanks a lot!