After wasting a day trying I finally succeeded, first to get Xcode to acknowledge that my watch existed and then to get into Developer mode. Most of the suggestions above will get you there in the end but there is something that needs clarifying. There is a "Developer" button that shows up at the bottom of the Settings screen. Tap that and toggle either or both switches in this screen. Then a "Developer" button shows up at the bottom of the Privacy & Security screen from which you can go through the setup process. Whoever thought this user experience was ready for release needs some remedial training.
Xcode 15.4 on M1 MacBook Air
Michael_Stone
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