The look and feel of the app itself is a CSS issue. There are web app frameworks that specifically offer themes matching style guides provided by Apple and Goog

The look and feel of the app itself is a CSS issue. There are web app frameworks that specifically offer themes matching style guides provided by Apple and Google. Framework7 is an example: the demo app on the home page is styled using iOS UI elements, and there is an option for more Android style designs as well. https://framework7.io/ https://framework7.io/