Wallet works in the Newton test network. Test Grams won't work in mainnet network.
After app installation there will be generated 24 secret words that you must store somewhere safe. With them you can access your wallet through Gram Wallet apps on any platform.
App source code: https://github.com/tginfo/wallet-android-newton
You can discuss the app or report bugs in our chat: https://tx.me/infotonchat