Advice on current state of multiple app "integration"

I know using the URL scheme to try to integrate apps i.e. you have one so call master app and then other apps would be called by linking to them. A common look and feel would be made so that a home icon call back the master app.

The app extension helps a bit but as we are developing a few apps under one organisation for the public, it is not exactly align. But this is something I am looking into.

The problem is that you cannot, say, easily farm out different small apps to different team to work on without user (i) (Under URL) feel there is a lot of handover involved and (ii) (extension) it is quite niche and limited.

Any advice in the current status of this kind of app integration or … well that is it?