In theory, I'm super attracted to this model. My only concern is that it puts a lot of eggs in the Firebase basket. And what happens if I need to scale faster

In theory, I'm super attracted to this model. My only concern is that it puts a lot of eggs in the Firebase basket. And what happens if I need to scale faster than Firebase can handle? Is there a way for me to run an in-house api compatible version of Firebase on my infrastructure and re-point to that? Can I keep a hot-swappable backup in sync? Or can I pay Firebase to do that for me?