In Mainland China I can't actually find anyone with a card reader to test this out. I saw one vending machine that allegedly accepted UnionPay but forgot about it and then other similar ones only accepted AliPay or WeChat Pay. I asked a hotel front desk to use it for a security deposit but they didn't have a card reader.
However I will keep trying for the sake of data points.
Tried to add it to AliPay, more details here:
https://www.flyertalk.com/forum/35226838-post370.html