I own a Garmin Fenix 6 Pro. I like it a lot and the GPS features are really cool. But, one of the known issues with the various Garmin watches is that the Heart Rate Monitor is wildly inaccurate. Unlike other brands of smart watch, Garmin can't make their HRM feature work. Garmin says that if one needs an genuine heart rate measurement, to use their optional bluetooth chest strap feature.
Also, I've read on various forums that the steps counting feature, when measured by testers using actual steps counted, has found to be inaccurate by a wide margin also.
The point of all this, is that if these guys are relying on the Garmin's HRM or other features for their fun and games with watches class, then they're building their program around fictional data.