Google may finally be ready to bring tap-to-pay to Android Wear, judging by evidence discovered in the Google Play Services version 10.0 by Android Police. Text prompt strings with messages like "Try holding your watch to the terminal again" make it fairly clear that Google is in the late stages of testing the feature. If you have a compatible Android Wear watch (one with an NFC chip), it will let you touch your watch to an NFC-equipped retail terminal to pay for goods.
Another new feature that appears to be coming soon is Instant Apps, a way to get apps (for one-time use or other reasons) without actually installing them. Android Police notes that the Instant App services have been switched on and a flag set from false to true, meaning the feature is likely being tested in the wild.
You can actually tap to pay on Android right now if you really want to, but you have to use a Samsung Gear S3 watch and Samsung Pay, ironically. That feature works on any Android device with KitKat 4.4 or later, because Samsung just made its payment service available to other Android smartphone brands, provided you're using its Tizen OS-based watch. The Gear S3 is equipped with the same magnetic stripe payment tech as Samsung's phones, letting you pay with the watch just about anywhere in the US. (iPhone users have also been able to pay with the Apple Watch and Apple Pay for over a year, of course.)
Smartwatches and wearables in general have disappointed of late sales-wise, and companies like Intel are reportedly scaling back development. It probably didn't help matters that Google delayed Android Wear 2.0, expected this fall, to 2017. Hopefully, Mountain View used the time wisely to improve the software and give folks more reasons to buy a smartwatch (and use Android Pay, which hasn't exactly set the world on fire either).
Despite its appearance in Google Play Services, you likely won't see tap-to-pay now until Android Wear 2.0 arrives early next year. It could arrive at the same time as a pair of rumored Android Wear watches designed and built by Google to be the smartwatch equivalent of its Pixel phones.