[kllrnohj]

Go would require building a whole new set of APIs and massive work since Go does not interop with Java.

Kotlin, however, interops with Java nicely since it compiles to jvm bytecode. So there's no new APIs to build and no transition performance costs.

Although that said you can actually use Go on Android ( https://github.com/golang/go/wiki/Mobile ) but since Go is native code you're stuck with Android's NDK or dealing with JNI and the performance costs of that.