> It stands to reason that Apple wouldn't have developed this feature if they weren't using it. Where? We have no idea.

If I had to guess, probably in the iCloud settings inside of the Settings app. Also in the App Store/Music/TV account page (when you tap on your avatar in the top right of the app.) A bunch of those pages have quite well hidden web views pretending to be native ones, mainly loading things from the iTunes backend services (the give away is normally that you can long press <a> links and a web page preview pops up.) It's probably being used for the user guide inside of the Tips app as well.

That's where I'd be looking at least.