I think this is interesting, but I'm having trouble seeing how it'll be used. Personally, when I want to do things like this - I roll my own custom solutions because I want more control. Given that, I guess I'll be giving it a shot (although I think Firebase in general is super over priced)
Fear based question: are there applications (hopefully mine) that would scale in an economic way? And there are other use-cases that wouldn't scale?