Earlier quoted context omitted.
Functional? I mean it does temperature, heart rate, oxygen, and body composition**. The asterisks are because let's face it, it's not very accurate. A cheap $30 scale will guess your body fat, bone density, etc just as "accurately". A dexascan is what I'd suggested over impedance guessing. To call the biometric sensor far more functional than the Apple watch is a big stretch, especially when you see actual comparison…
I never understood those scales. Let’s imagine they have a perfect formula which can correlate electrical impedance to fat %. But the electrodes are on your feet, so the very best it can measure is the shortest path up your leg and down the other side. Less than half your body.
The US navy devised a formula based on height age and your neck and waist circumference and was 2-4% accurate for body fat calculation (it's not good for tracking relative changes tho).
You can make generally fairly accurate assumptions about body fat percentage from a few key indices when it comes to general population.
The electrical impedance issue becomes more problematic when you have a higher muscle mass vs fat mass as the scale has a much harder time figuring that out (which is why some of the scales have an "athlete" mode on them).
Most of the good scales also have a handheld impedance sensor on them to track upper and lower body impedance for a more accurate measurement tho.