Powerwall Companion X is a Xamarin Android app for monitoring your Tesla Powerwall 2 battery. It has similar functionality to the official Tesla app, but it's designed to be more of an "always on" dashboard, running on a spare device. This is an Android port of my older Windows UWP version of Powerwall Companion, which is avaiable here.
The app is available to download from Google Play here. The store is the easiest way to get the app, but I'm sharing the source in case anyone wants to improve it or is curious about the underlying APIs.