Right now, using web portals is indeed better than installing apps, but this does not have be the case. In fact, it should be the other way around.

You only need to make two changes to make your native app a better choice than your web portal, even for privacy:

1) Make your app open-source, and remove all the tracking.

2) Don't make a web portal. Your website should just be a website that displays information, not 5 MB of JS+WASM with a load of security issues.