Watch Feeds does not collect any user data from your device if you are not using "Sync Read" as your RSS source provider. When you use Sync Read, you need to sign in using "Sign In With Apple." Apple will provide Watch Feeds with a unique identifier. Watch Feeds will store this unique identifier (Yes, just an identifier, this mean the server won't even know your name, email, Apple ID) and your subscriptions & read articles ID to Sync Read server. If you enable push notification or complication, Watch Feeds will also upload your subscriptions to our server so we can access the feeds periodically and send you notification/complication when there is a new article. But other than that, what happens on your watch will stay on your watch.