What problem does this feature solve?

NativeScript recently introduced two new components Tabs & BottomNavigation that are considered a better version of the old TabView.

Currently vue docs do not have any content on the new components and nativescript-vue devs might not even know they exists.
For reference you can check this blog post here: https://www.nativescript.org/blog/tabs-and-bottomnavigation-nativescripts-two-new-components.

What does the proposed API look like?

Documentation articles like those for NativeScript Core & Angular:
https://docs.nativescript.org/ui/components/tabs
https://docs.nativescript.org/ui/components/bottom-navigation
https://docs.nativescript.org/angular/ui/ng-components/tabs
https://docs.nativescript.org/angular/ui/ng-components/bottom-navigation