There's the typical video production apps like FilmoraGo or KineMaster, but these aren't strictly animation; you couldn't make an explainer video with it if that's your goal.

If you're instead looking to design an app for Android, you'll want to look at Figma and Adobe XD. Figma has some pretty good prototyping too.

We use Figma for most of our UI animations at Vidico. See most of the examples of the homepage for an idea of what I'm referring to: https://vidico.com/