[sanderjd]

My take is that Java -> Kotlin was a very natural progression, as they are very similar languages with an identical runtime in the jvm. Kotlin is just a better Java, which is incredibly easy to adopt into an existing Java ecosystem.

But then they also wanted a more bare metal environment in addition to that. So something like C, C++, or Rust.

It's always been unclear whether Go belongs in that list. It was conceived or at least positioned as a "systems" language like those I listed, and there was noise early on about it replacing C++ codebases at Google, but with over a decade of hindsight now, I think in practice it's pretty clearly a Java replacement rather than a C++ replacement. (I guess there's a fun symmetry here in that Java was also conceived as a C++ replacement and also wasn't.) But Kotlin is just a much more natural way to fill the Java replacement niche on Android.