As a Rust enjoyer, I wouldn't get into Java at least without being forced to (better is not good enough in this case), but Kotlin seems neat. The only thing that has been blocking trying it out is that the non-IntelliJ experience has been rather poor.

this will change, Jetbrains is working on a Kotlin-LSP, just don't expect it to be done anytime soon: https://github.com/Kotlin/kotlin-lsp