How much of that is limited by the API that Google is surfacing? Watches simply cannot compete with an Apple Watch because Apple doesn't surface the same functionality for any other device.
Why does less competition make you less concerned about anti-competitive behavior? Such behavior is never good, but it's self-correcting in a market with lots of choice, and not so in a market where there's only one great option (a judgment for which I have to take your word—a Casio F-91W is the right level of watch technology for me).
My point is, nobody seems to be fighting for this market except Apple. I could just be naive here, but it doesn't seem like anyone else cares enough for Apple to be anti-competitive.
You're right; I used the term "anti-competitive behavior", but that was the wrong word for what I was trying to say. I meant rather the lazy behavior of an established giant that doesn't have to compete, and so is content to let standards slip since they can be reasonably confident that it won't lose them any, or many, customers.
It would be nice if Apple would make the watch accessible to people without iPhones. I would certainly believe their rhetoric about the importance of health tech if they did that.