Measuring human weight is harder than it seems (we don't stay still).
Most scales use a strain gauge sensor that detects bending of a metal arm through changes in resistance. It's pretty noisy and needs averaging. There's some integrated circuits to relate the resistance to weight. Most do some factory calibration only around the target weights (median adult weights).
Look instead for a scale that explicitly states that it is accurate over the whole range (e.g. baby to 220lbs). Usually there's tradeoffs - e.g. the displayed weight won't 'settle down'. I have one like this and it works better than any previous one I had (tested by adding calibrated weights), but I hesitate to recommend since it's a low cost consumer model.
Accurate enough for weight control (doesn't drift from day to day), no "stuck weight" problem mentioned either. Just need to wait 2 seconds for self calibration to finish
Humans are constantly changing weight, with every single breath you take.
I also tested on small weight and what my kitchen weight calls 3.016KG my bathroom weight calls 3.0KG so I'm pretty sure it's still reasonably accurate in absolute scale.
You need to weight youself and then weight yourself again with something of known weight in your hands.
Floor scales usually aren't good at a small weights, though I wouldn't be surprised if they are not bad at it nowadays.
Personally, I've only ever had one scale in my life that I thought might be using memory to give false consistency. But even then, it was short-term, not long term. I.e. if you stepped off and back on, it might bias towards giving you the same weight. If you walked away for a bit, then came back with a small extra weight in your hand, it was accurate.
It has wifi and bluetooth, so it always syncs up with your phone and can track multiple people. I don't really trust the body measurement stuff but use it for measurement per measurement information. The heart rate is kind of nice to track too.
0. https://www.theverge.com/23573362/anker-eufy-security-camera...
The only project I found was FitScales and it has been dead for a long time now because Android Bluetooth changes made it incompatible with newer devices.
The bodyfat measurement is good enough to be usable and the same scale is working in our household for almost 10 years now I believe.