SpriteKit Custom Watch Faces...

Note point 4.2.4

https://developer.apple.com/app-store/review/guidelines/#minimum-functionality

• 4.2.4 Apple Watch apps that appear to be a watch face are confusing, because people will expect them to work with device features such as swipes, notifications, and third party complications. Creative ways of expressing time as an app interface is great (say, a tide clock for surfers), but if your app comes too close to resembling a watch face, we will reject it.

 

These aren’t going via the App Store, you just install it on your personal watch.

So the developer guidelines don’t really apply.

 

I'm aware of that. I'm just pointing out the limits in case folks think this is somehow going to open up new watch faces via the app store or potentially waste effort of creating something with that in mind.