On App being phased out as it apparently doesn’t work with iOS 17: the Companion App replaces it.
Unless you’re in particular need, I’d be tempted not to install it at all though: as the basic treble tap functions seem to cover most of the stuff you’d need to change on a day to day basis.
It works with iOS 16. Pephaps this is some kind of incompatibility, and the On app will be updated. As I understand, the Companion only works with Reals, older models work very slow with Companion.
@lgbuck62 Companion app works with my apple watch, as long as I leave the app running (in the background) on my phone. However you have to hunt for a watch face that it works with - I haven’t found many.
Edit to say I have the More 1’s. Not sure if that makes a difference.