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.

You cannot use an Apple Watch without an iPhone. Family Setup isn't convenient because you will have to add every participant to your own personal family. I am not very experienced, but I think an app that extracts data from their Health app and sends it to your server and maybe there's a possibility to make this happen. If you cannot send data to your servers you can prompt users to send a report to you via Mail or some other way. I am not 100% sure this is possible but there is room for this. Good luck with your project if you want to make it reality!

Maybe the watch isn't connected. Make sure both devices are connected to the same network and try again. By the way, this is the Apple Developer Forum, and your question is not related to iOS / iPadOS / macOS / watchOS programming. To post your question on the standard Apple Support Communities forum, click here.