Interesting idea, so I had to check!

Prompt: “Top language pick for an Android app? Respond with only the language.”

Responses (admittedly via the aichat CLI, not an agent harness; and temp=0):

Kimi K3: Kotlin

GPT 5.6 Sol: Kotlin

Claude Fable 5: Kotlin

DeepSeek v4 Flash 0731: Kotlin

Are there any other “inherently” heavily JVM-biased domains?

I think even in Minecraft game mods Kotlin is possible nowadays…