The Apple Watch zwift companion app is very buggy and often drops my heart rate which is a major annoyance. WatchOS 10 includes a new API that integrates with Apple Watch workouts. Maybe this would be a way for zwift to work with the watch better? TrainingPeaks has done this
theverge .com/2023/12/14/24000034/apple-watch-training-peaks-fitness-wearables-custom-workout