Just a quick post.
I have been looking for light switch solutions for quite some time, I use connected light bulbs rather than controllers on the lighting circuits which means I end up with annoying light switches that don’t integrate with anything.
To solve this I combined a momentary push light switch with a cheap Xiaomi button to make a smart light switch that looks “right”!
The lighting wires are connected together in the wall box so the bulb is permanently on but thats what I did anyway.
If anyone is interested I have a video on the conversion but it was a very simple process, not sure why I didn’t try it sooner.
It’s very clever, and I want to like this, but I’m concerned that it doesn’t meet fire safety standards as it looks like you have put the battery operated device in right next to the live wires even though the battery device is not controlling the current load.
Batteries can and do outgas and corrode, which is why typically battery operated devices are not embedded in a wall unless specifically engineered for that purpose.
This explains the form of some of the battery operated devices like the hue dimmer switch. They are not going into the wall, they are going on top of it.
For your device, instead of just putting it into the switchbox, it would probably be best to blank off the switch box and then mount the battery operated retractive switch on top of the blank, so it is up above the wall surface.
But I really like the whole idea and the end result. It’s just the internal engineering where I would like to see the battery placed farther away from the wires.
If you haven’t had a chance yet, you might take a look at the following report where someone made a blanking plate so they could put a Popp switch over the top of it.
Your solution would be much less expensive and accomplish the same thing for basic on/off, so I think many people will be interested in it. And the blanking plate approach helps address the fire safety issues.