To add notifications to the Notification Summary on your Apple Watch Ultra:
Add Notifications to the Summary
1. Swipe left on a notification and tap More.
2. Tap Add to Summary.
This will add notifications from that app to your Notification Summary on your iPhone going forward[1][3].
How the Notification Summary Works
The Notification Summary is a feature on iPhone that collects notifications from apps you specify and delivers them at scheduled times, like in the morning and evening.
When you add an app's notifications to the Summary on your Apple Watch, they will be delivered to the Summary on your paired iPhone as well[1][5].
You can customize the Notification Summary schedule and which apps are included in the Settings app on your iPhone under Notifications > Scheduled Summary[5].
So in summary, swipe left on a notification on your Apple Watch Ultra, tap More, then Add to Summary to include that app's notifications in your iPhone's Notification Summary going forward. The Summary collects notifications and delivers them at scheduled times to reduce distractions.
Citations:[1] https://support.apple.com/en-us/108369
[2] https://support.apple.com/en-in/108369
[3] https://support.apple.com/en-gw/guide/watch-ultra/apd9b833c9f3/watchos
[4] https://support.apple.com/guide/watch/see-and-respond-to-notifications-apde978ebff5/watchos
[5] https://support.apple.com/guide/iphone/view-and-respond-to-notifications-iph6534c01bc/ios
[6] https://support.apple.com/guide/iphone/change-notification-settings-iph7c3d96bab/ios
[7] https://support.apple.com/en-us/108781
[8] https://www.youtube.com/watch?v=Xo4F-MiBPIs