Pushing updates without going through the app store has been allowed by Apple as long as the assets being updated are not binary code; specifically CSS, HTML, and JavaScript are okay (I wonder whether WebAssembly will be considered "binary" or not... will be interesting to see). I convinced a former employer to abandon their Xamarin-built app and switch to Ionic (Cordova with nice, fancy UI additions) specifically because they could push updates to the app without going through the app store. Officially (unless things changed?) the Google Play store says this isn't allowed but there is no review process with Google Play so publishing a new app and then pushing an update for the previous version won't likely get you in trouble. If someone HAS been busted by the Google Play cops for this it would be news to me.