I had a use case that I wanted solved for automatically tracking how much crypto I own on exchanges that hasn't been done by any other apps/websites. Used it as a learning/side project, and got the mobile apps on both app stores (they're not as picky as you would think, especially the google store). User base of 1 (me). Web app/api in rails. I used create-react-native-app (Expo) and have not ejected yet. It's an awesome developer experience live reloading your device wirelessly. The biggest difference between react and react native is what lives in your render function: instead of <divs> you have <Text>.

2019 will be elixir+phoenix (finally). I plan on creating a self hosted RSS reader with the new phoenix live reload module that should be pretty slick