I have same problem. I stick to my trusted Garmin for runs because my Apple Watch 6, I don't have physical button to stop the watch.
Once I was completing my first half marathon, quite a milestone for an apek like me and when I tried to stop the run on my AW6, the screen is not responsive to my wet fingers and I can stop the run. I need to also swipe the screen to press stop and the screen cannot swipe/slide. Luckily I wore 2 watches together my Garmin.
With the Ultra, we can stop the run by pressing both the Action button and side button simultaneously ?
Another gripe that I had with the AW6 is that it doesn't have a metric to monitor my max HR. Can the Ultra do this now ?
To solve this, I bought the Walkoutdoor app and installed. But not sure if we can configure the Action button to stop the run in the walkoutdoor app ?
Thanks