Question: Current library capabilities on android app

[SkyfaceD]

I'll already a little bit played around this library. And drew following navigation diagram of my expectations:

Maybe I'm not correctly described navigation flow or simple not understand jetpack compose (I'm working on it). And now I have several questions:

1. How I can manage visibility of BottomNavigation when open concreate screen inside any tab? I can do it by passing callback, but it's hard to manage actual state with such approach. Also, theoretically, I can try to save each navigator of tab navigator and pass it to parent screen and then iterate over it?
2. Why onBackPressed() not actually finishes app?
3. Not a big problem but is there any way to close app using navigator?