I haven't seen it in action when paired to an Android phone, but I get SMS, Facebook and Instagram notifications, can dictate to Google Assistant, I get the Google Fit data on the watch but haven't checked if it syncs (I don't use fitness data), Google Maps works, I get calendar notifications. Only thing I've had issues with is Strava, which worked before the latest update. I can't seem to get the account to sync but I suspect it's a Strava thing, not an iOS thing.
In my opinion, the iOS app thing only became a thing because some people thought they were being short-changed without it. If you use WatchMaker for watch faces if you want to, then I'm not aware of any actual features that you miss out on with iOS.
It's a great watch (I'm on my 2nd one lol), and really looks and feels fantastic on. My only wish is that when the next generation comes along, that it's offered as a module so we can upgrade at a lower cost, or that they release a Calibre 01 mechanical module for it (as I find the mechanical Calibre 5 module option a little bland).