Hong Kong region of the Google Play store can now add the mainland UnionPay card in the “payment method”.

▲ Thanks to @softmedianewcomer2016930 for the picture.
According to the screenshots provided by users, the “Payment Methods” of Google Play Store can now bind the UnionPay debit card of Chinese banks. According to a discussion in the V2EX forums, debit cards from banks such as ICBC, China Construction Bank and China Merchants Bank are also available.

▲ V2EX-related discussion screenshot
Previously, local users in Hong Kong could choose from local credit/debit cards, PayPal, AlipayHK and Octopus to complete their transactions.
As for the bundling method, when adding a Mainland China UnionPay card, you need to enter the bank’s bundled cell phone number to receive the SMS verification code. In addition, the process can only be done through the Play Store on mobile, and attempting to add a card on the web will still result in an “invalid card number” message.
It’s also important to note that the feature is still suspected to be in internal testing, with only a small number of users able to bind a UnionPay card.