I think iPhone 14 can only pair to Apple Watch Series 4 or later. Try asking this question on Apple Support Communities. FYI, this is a developer forum; for asking questions to other consumers and not developers, use Apple Support Communities.

I also need help implementing Push To Talk into my app, and having the demo app's source code would help a lot. Searched a lot today and haven't found anything. Can anyone help with the source code if they have it?

Really sorry to hear that. I can't imagine how disturbing it can be. Does your app use any private APIs? Not sure if that's the reason, but you may want to double-check. Can you reach out to Apple to ask for more information? If they provide more info, make sure to keep us updated. UPDATE: It looks like you're not the only one experiencing this issue. Here is another thread describing the same exact issue.

Try reinstalling Swift Playgrounds. That worked for me.