From my modest experience with Kotlin few months ago in a small Android project for learning purposes. I can just say that the language resulted very expressive, concise and easy to use for me. Coming from other languages (Go, Rust, C#, JS, PHP among others) but doing almost no Java in the past, I was able to getting started with that Android project few weeks later after have been passed across Kotlin's docs https://kotlinlang.org/docs/home.html

So basically I can confirm "Android’s Kotlin-first approach" https://developer.android.com/kotlin/first