What's great for kids, in my experience, is with scratch they can "see things happening", making simple animations and games, and exploring. Also, scratch isn't (to me) missing anything -- it's a full programming language, the plugable blocks just ensure you build "by AST" instead of by text, which honestly is a feature I've heard language designers suggest we should move to (it would once and for all get rid of formatting questions if everyone could do AST -> On-screen visualisation themselves).

With this language they can... implement functions like reverse, append and length by themselves?

I don't mind people exploring options, but please don't insult Scratch, then make up something for kids which (as far as I can tell) has never been shown to a kid.