So I've got an available slot in a three gang box after doing some rewiring. My under Cabinet lights run off a smart plug that's plugged into the fridge outlet (sue me). Basically what I'm looking for is a button that I can rule machine up to toggle the state of the smart plug. Or have unique signals for on / off. Whatever really.
And I'd really love for it to be able to fit right into a single gang space and run off batteries.
I've repurposed uneeded 3-way traveler wires to bring power into the box on occasion. I'm sure you would have done that if possible, but just throwing it out there just in case.
Otherwise, yeah - the Zooz previously referenced. I think toggle switch style is going to be difficult - limited options.
If you still need something like you asked for, I think the Hue in-wall relay might work (it's powered--a bit odd for this kind of device). But if you do have a neutral, lots of in wall relays would work, like RGB Genie or (if I don't mins Z-Wave) Zooz or others. Most would let you keep your existing switches if matching appearance is important. Or there are also a few toggle-looking switches and dimmers, though they might stand out a bit more since all I'm aware of rest in a mkddlw position.
I had a blank plate in my living room. When I opened it up there were two 50 year old switches mashed into the back. One was crushed. When I removed them there was still power running to the box. It was a little unnerving.
I don’t know what the original purpose was but I removed the switches and cleaned up the wiring. I then installed an Inovelli switch. It isn’t connect to any load but I use it as a button controller.