What’s the Google one? Flutter?
Angular.
Flutter hardly matters.
You say that, but Cloudflare just rewrote their WARP / Cloudflare One clients in Flutter. It really sucks, but they are using it.
I don't even know what that is.
Flutter is the only reason Dart still exists, and in what concerns the Android team, writing cross mobile application, is to be done with Kotlin.
Which contrary to Dart, has a few use cases, besides Android.