Which series of Apple Watch and Watch OS support Apple GymKit

North Pole Engineering's GEM2NFC and GEM3NFC modules include support for Apple GymKit. Apple GymKit support was launched with WatchOS 4.1 and works on Series 2 or newer Apple Watches.

To enable GymKit on a compatible Apple Watch, go to the settings app, select Workout, then turn on Detect Gym Equipment.

https://support.apple.com/guide/watch/use-gym-equipment-with-apple-watch-apdf855bb3c0/watchos