This app was mentioned in 2 comments, with an average of 1.00 upvote
I've just discovered that the guys at Numix have an app template for situations just like yours. I did not dive into that very deeply, but it seems rather simple. If you want to give it a shot here's the link at Play Store: https://play.google.com/store/apps/details?id=org.numixproject.example.webview.pro the template is available via gitHub in the app description. Good Luck!!
You can make offline webapps.
e.g. on Android: https://play.google.com/store/apps/details?id=org.numixproject.example.webview.pro