Can't say I've heard of anything like that, though that doesn't mean it doesn't exist somewhere.
It's technologically feasible, but I don't think the economic demand is there. Most folks don't want to publicly broadcast their current weight.
There's also how the weight can vary throughout the day, so the only way to effectively perform long run tracking is to weigh under the same circumstances every time, ideally shortly after waking up.
It's also physically impossible for a scale to ever accurately measure those other things besides weight. For all it knows, you could be carrying 20 lb barbells in each hand.
If you're really, really determined, I could imagine making your own digital scale but that would get complicated, technical, and likely expensive, fast.
Alternatively whatever Bluetooth scale with an app like that, maybe you can reverse engineer the Bluetooth signal somehow. But I don't know how time consuming this would be, or the amount of trial and error required.
I really doubt the protocol API over Bluetooth to interact with the app would be open source. For all I know, on some of them it might be encrypted, though goodness knows why, if so.
But then, even if you do that, you'd need something like a RaspPi to accept the Bluetooth signal. You would then need to write a program to take this data, and upload it to a web site you pay for.
This kind of RYO solution, I don't know if it's feasible for you. I know it would be beyond the knowledge of probably most folks.
23 hours
