All of those examples (except maybe tensorflow, I don't know enough to say for sure) are interesting because they highlight a more "googly" approach to the prob

All of those examples (except maybe tensorflow, I don't know enough to say for sure) are interesting because they highlight a more "googly" approach to the problems. Typescript is a superset of javascript, Dart isn't (though it transpiles). Flutter implements its own widgets, react native controls native widgets.