FWIW I had some success (I can now install my app to Apple Watch Ultra, but I of course cannot debug) by doing
Close XCode
Go to /Users/username_here/Library/Developer/Xcode/watchOS DeviceSupport
Duplicate the folder "Watch6,9 8.7 (19U66)"
Rename the duplicate to "Watch6,18 9.0.1 (20R8380)"
Start XCode again
Now I can at least do some limited testing on the Apple Watch Ultra. This is with XCode 14.0, WatchOS 9.0.1, on MacOS 12.5.1, no additional Beta profiles
Topic:
App & System Services
SubTopic:
Core OS
Tags: