According to Mozilla's privacy not included page, Garmin smartwatches aren't that terrible at privacy.
I'm also in the lookout for a non-privacy-invasive smartwatch with contactless payment support and ideally with cellular connection and capable of replying to Signal messages while disconnected from the phone, so that I can leave the phone at home when I go to the beach. I currently have a Galaxy Watch with LTE, but I stopped using it because of the privacy concerns.