Maybe the USB connection is properly isolated?
In that size and space, and given that it has to have isolated charging as well and not just comms, I greatly doubt it. But I could be wrong, charging current won't be high.
Yeah, don't know about charging current. If low enough, it's definitely doable, but the usual solutions, in order to fit in that space, would have 1/ pretty low efficiency probably, 2/ not that cheap and 3/ would be hard to tame EMI-wise. So, yeah, I also have some doubts they really did isolate it.
Other than engineering issues, the whole point of this kind of meter is still questionable IMO. Oh well.
But people love the concept, that's why they buy it, not because it's of more value than a pen multimeter.
Well, I can tell there is demand for that, but I'm very wary of the long-term interest. This is typically the kind of device that some people will be excited to buy, then they will use it a few times, lose interest (because of all the shortcomings, and the not-so-great usability after all), and it will end-up in a drawer. So I'm under the impression that this kind of multimeters are not meant for the long term, neither for the user, nor for the manufacturer; just to be sold in enough quantities for a couple years, and then the company would move on to the next venture... just the way I see it.