I love the idea. Scares the shit out of me.

I’m not as concerned with these things starting house fires, but I want to explain that away first. I’m a little weak on the science, but my understanding of how these work is that they attune to the grid frequency and voltage to deliver power at a slightly lower frequency than what is provided by your wall plug. This allows them to augment your home power use without refeeding power into the local grid. IIRC, if there’s no wall power, they only offer power through outlets on the devices themselves, vs through the wall plugs.
And, I think that the above safety feature will prevent over-amperage situations for in-house wiring loops, since the device cannot exceed the power delivery of the circuit it’s plugged into, when operating normally.

These things scare the shit out of me because the U.S. power grid is badly under-engineered. Before actual electrical engineers hunt me down and kill me, think of building a bridge. You can do that by just pouring a billion tons of concrete into a ravine. But building something that is material and budget conscious while being safe enough to avoid lawsuits is not what I’m getting at. (Think of a bridge the phrase “Anyone can build a bridge, but not anyone can build a bridge that barely stands.”)
It’s a feature, not a bug. Otherwise, power lines would be I-Beams and we’d have some sort of insane switching technology to isolate and shut off every single segment of the grid.
But we don’t! Homes are never disconnected from the grid unless specialized hardware is installed at the meter to disconnect them. (Which happens for distributed/co-generation scenarios.)

The existence of always connected power generation or storage sources as a potential threat vector is well known. In 2023, it caused a minor kerfluffle as several brands of EV chargers were shown to be easily hackable and as few as a few hundred of these could be used to take down a regional power grid. Not everyone can afford an EV, and usually those users are a tad more tech savvy. They generally are not buying third party chargers, anyway.
But the rate of adoption for these devices could be significantly higher. The law of averages being what it is, I think these pose a much higher threat to the grid from hacking. Everyone loves apps. No one thinks about security. They could easily exploited, rooted, and have their safety features disabled. Who needs 300 EV’s when you have 300,000 balcony chargers?

Funnily enough, these would be in high demand if the U.S. grid got fried. It would take years to undo the damage.