Having NFC and google pay are two really different things. A watch would have to be able to run external apps to run Pay, not just have the hardware, and the new watch runs a proprietary OS, which means it will not be able to. The NFC on that might be used for other things, but always within the limitations of the OS (ie, if redmi has partnerships with the card providers and can code it in)

but can I use Google Pay on the watch?