Well, that's the end of that. After purchasing a Galaxy Watch 4 and becoming 'that guy' who buys everything buy waving his wrist at the reader, It was great. Then shock - error sound from the watch, unable to pay/software version compatibility error... No indicator on the watch to suggest anything is wrong, 3 weeks later I still can't pay. Gone back to debit card, srsly errors like these shouldn't be a thing - I won't be relying on Google Pay again, but it was a nice couple of months.