I'm not so sure about that, yes it's an important language and has oficial support from Google, but by the amount of usage we can say Dart ( in Flutter ) also "replaced" Java on Android.

Don't get me wrong I HATE Java on Android and everything GUI related, but I'm don't think Java will be replaced anytime soon.

Not sure I agree with that. More on "Android’s Kotlin-first approach" is at https://developer.android.com/kotlin/first. I haven't heard the same about Flutter and Android's new UI toolkit, Compose, is written in Kotlin.

Has it really? (Totally honest question, I don't follow that space well.) If Some Random Company is starting a new Android app today, is it more likely to be in Kotlin than Java? That's cool, if so.

Yep! Been this way for a little while now. More detail at https://developer.android.com/kotlin/first...

as someone who's been writing Java for Android since 1.0 (but not much recently)

my main pain point with it was more the API rather than Java (e.g. the activity lifecycle, the 20 layers of compatibility stuff, contexts everywhere)

did this clear some of that up?

Not really. It just another language, but, IMHO, threads have gotten A LOT better through Kotlin’s Coroutines. That said, the libraries have gotten a lot better and the new UI toolkit, Compose, addresses a lot of shortcomings, but it’s still early.

Kotlin has a lot of features aimed at mitigating the pain of working with Java APIs, such as extension functions. So you can sort of fix the API in a library or in your own code. (But it doesn't help with the lifecycle or reducing the number of layers.)