Question about Samsung Galaxy Watch

Yes, you don't need a smartphone or an internet connection to use it at the checkout. You can really only pay with the watch.

A smartphone is needed for installation and credit card management. However, it can also be from a non-Samsung brand. However, the Gear app must be installed. The credit cards are managed there.

The watch stores about 10 tokens for offline payments. This means that after about 10 transactions at the latest (without a smartphone connection) at the checkout, you should go near your smartphone again so that it can synchronise and load new tokens for new payment transactions.