One of the tiles on the buy page says "HR BAND SUPPORT Connect compatible BLE chest straps". But one single connection type doesn't compare to Garmin's list of supported ANT and BLE accessories.
I have an Amazfit Balance, and previously several Amazfit Bips. I really like being able to use my watch as a BLE heartrate monitor with iSmoothRun on iPhone. I gather that being able to do so is not typical for smartwatches.