Navigation. Are we supposed to have one big router for handling the whole navigation in the app or multiple small routers?

In general, 1 big router for the whole application. I’ve found navigation gets really messy and difficult to understand when routing is done with things like a hierarchy of routers. But you may have some screens in your app with tabbed views, multi-page flows, etc. You’re free to create sub-routers as necessary for those features, but don’t really think of them as “nested routers” as would be common in other libraries. Instead, just treat them as their own isolated thing that’s just a feature of that screen, unrelated to the main app router