I have never tried this, as I am happier with RFID on my individual credit cards.

However, Google Pay will certainly run on my Lineage OnePlus 5. It will not provision localhost, but I am guessing that it will provision a watch.

I would go buy the parts and try it just to know, but I doubt interest would remain here by the time I assembled everything.

Edit: Graphene has a page on this subject, and Garmin appears to be the best option.

https://discuss.grapheneos.org/d/1040-compatibility-with-sma...