Oops! I didn’t realize in an OP’s thread that we’re only allowed to discuss what the OP is interested in. Sorry 'bout that! My comments were more in response to what cvkemp said about connectivity and performance with the iPhone and the Apple Watch, not in response to anything you said.
One funny thing about HA apps no matter where from is they all seem to fare relatively badly compared to many other types of apps for iOS or Android that are often rated much more highly, e.g. 4.4, 4.6, average stars, etc., in app store ratings. It’s been a while since I’ve checked but in the past, it was hard to find a HA smartphone app that even rated close to 4 stars. I wonder if it’s many HA users having paid a bundle for premium HA’s expect a stellar smartphone app to go along with it - or what? - and apparently based on ratings for most HA smartphone apps, users aren’t finding what they expect.
I don’t think that you can divorce an app from the platform that it runs on, even though you might like to. The HA, the smartphone, and the app are a three-legged stool (or a 4-legged table, if you throw in the Apple Watch!). It’s how they interoperate that determines the user satisfaction with the app and maybe how far you can take the app. I wonder if it’s harder to interface some HA brand firmware with MFi than others? Other HA brands have had quite a few years to come around to the MFi standard on the iPhone but since it was originated between ReSound and Apple maybe that has something to do with relative performance, not dropping connections, etc. (although connectivity problems do happen with ReSound devices, too).
I didn’t want take the thread off topic, just to suggest in the three-legged stool view, I would bet it’s the ON app that needs to be improved the most - not that Apple is entirely blameless as shown by iPhone 12 problems, etc.