I do kotlin daily, almost exclusively including side projects.

Kotlin native has been rocky personally, I'll check back in a year.

Kotlin on Android is a must compared to Java, else you're a fool. Haven't seen any exceptions in the industry.

Kotless is okay, works, but early days.

I've seen decent backends on quarkus and kotlin.

It's a fun language, the couroutine development is pretty nice. Flow is a lot easier than Rxjava.