https://www.theverge.com/2018/3/16/17128906/google-pay-wear-os-devices-canada-spain-australia

Google Pay can now be used with Wear OS devices (the new name for Android Wear as of yesterday) in Canada, Spain, and Australia, as spotted by Android Police. Previously, the payment service was only officially available on Wear OS devices in the US and UK.

As Android Police points out, enforcement for use strictly within the US and UK had been somewhat lax, with people in other countries using the service without issue. However, those who installed the Oreo update on the Huawei Watch 2 found that their ability to use Google Pay on the device was then disabled outside of the US and UK.