I'm using a Fossil watch running WearOS, which essentially provides a certified pathway enabling NFC payments via Google Pay/Wallet. The WearOS app running on GrapheneOS (on my phone) is able to provide the necessary bridge to let me transfer card details to the watch.
Once the card details are stored on the watch, my understanding is that it operates as an officially-sanctioned clone of your card. It's very convenient, though it's going to be leaky. Then again, privacy can best be maintained by using cash.