This Xiaomi thing is so mind-boggingly stupid that it hurts.
The main points you're making are all good points, and they basically converge to this device being completely unpractical.
Still something that tickles me here. You're saying that this thing can be made safe. That, IMHO, remains to be seen. Do you really want a several-hundred Watts 5GHz emitter in your own home? That's crazy.
I suggest the following reading:
https://pubmed.ncbi.nlm.nih.gov/17929264/Penetration @5GHz may look marginal, but it still seems enough to penetrate the dermis layer. With such high-power emitters a couple away from you for extended periods of time, I would personally not sign if I had to take responsibility for the consequences. I just don't know, and from the last studies about this, it still seems unconclusive, which means we don't know. Hundreds of Watts is a fricking lot of power.
Beyond safety issues, I'm also curious how you can design such a device, again for "home" use, while passing all correspondingl EMI and RF regulations. That's probably very tricky. Managing that would look like a feat of engineering.
Now I can see why this is the holy grail of electricity distribution. Many people probably see the future of that as houses with only wireless electricity transfer, and no plugs, for which this thing is just a preamble. Tesla envisioned the exact same thing a century ago, and it didn't really end up well. Sure technology has dramatically improved, but the laws of physics look stubborn.