Great question! Unfortunately, there is no direct way to make an Apple Watch alarm ring on your iPhone instead — alarms set on the Apple Watch only sound on the watch itself.
However, here are some workarounds to achieve what you want:
1. Set the alarm on your iPhone instead: Alarms set in the iPhone Clock app will ring on your iPhone (and your Apple Watch will also show a notification for it). This way, your phone rings while your Apple Watch continues tracking sleep silently.
2. Use iPhone's Sleep/Wake Up alarm via Health app: In the iPhone Health app, go to Sleep > Full Schedule & Options > set your Wake Up alarm. This alarm can be configured to alert on your iPhone, and your Apple Watch will just track sleep in the background.
3. Disable alarms on Apple Watch: In the Watch app on your iPhone, under Clock settings, you can turn off "Push Alerts from iPhone" for alarms if you want your Apple Watch to stay quiet and only ring on iPhone.
4. Use Do Not Disturb on Watch while sleeping: This won't ring alarms on iPhone but will keep the watch quieter for other notifications while Sleep Focus is active.
The Sleep tracking on Apple Watch runs independently regardless of where the alarm sounds, so you can safely set alarms on iPhone only and still get full sleep data from your Apple Watch.