Few additions to this topic as mobile developer:
1. Website is awesome, sure, but it will never replace feeling of a native mobile app. Starting with fullscreen (on my Chrome after pinning to homescreen I am simply redirected to chrome and the page is opened). It's not just push notifications. Touch feedback, response time and a lot of other things are making native app better than some hybrid stuff.
2. Wrapping in Ionic, Cordova and stuff is some kind of solution, but each forum should have it's own icon, etc. There is a lot of problems to solve, not to mention these frameworks have a lot of issues and development is endless.
3. Creating a mobile app isn't only embedding forum in webview, We should also have page to type forum address and some kind of switcher between multiple forums (like teams in slack). Another thing to create and maintain.
4. Creating mobile app is expensive, maintaining app is expensive. I see developing forum alone is expensive enough. And I'm not talking programming only. Each app should have a little different UX, depending on platform. It's a lot of work.
5. Nevertheless, if somebody would like to create mobile app (with UX guidance from Franz or Toby, though), I'm happy to help.