These resources might be helpful:

• Expo Deployment Docs: https://docs.expo.io/versions/v34.0.0/distribution/introduction/

• React Native - Android App Signing (Non-Expo): https://facebook.github.io/react-native/docs/signed-apk-android

• React Native - Building the iOS App: https://facebook.github.io/react-native/docs/running-on-device#building-your-app-for-production