Yeah, Kotlin is stuck in an uncomfortable position, like F# is in the .NET world. It has pioneered several important features, but now the big brother has implemented them slightly differently and people demand interop from you.
At least Kotlin can theoretically retreat to Android.
I did a decent amount of AoC this year in F#. I felt it was more verbose than I would have expected. There were a lot of things that helped brevity; I really liked type definitions, unless I was using OO features where it was extremely verbose to define members. I also really didn't like having to to Seq.map or List.filter for everything instead of just calling methods off of the seq or list.
At least Kotlin can theoretically retreat to Android.