I’ve tried to build some test Android apps using the Ionic. And by enabling install from other sources than Play Store, virtually anybody could install and test my app provided one has an Android device. Sending Dropbox link to a friend with Android device is a hassle-free process.
I am not so keen of keeping two codebases for the same purpose, but I am experimenting with a new approach, where server renders the simple document using the same data, including the web-app script and serves the same data in AJAX requests of the provided web-app.
Language diferences for building any web apps:
on server: HTML + CSS + PHP (or any language of your choice like Ruby, Pyton, Java, ASP,…)
If you are lucky, your host supports Node.js and reuse of templates is very doable. But most of the time you can consider yourself lucky when your host is running latest PHP codebase.