I have standard Decora wall switch at the door to the garage. That old fashioned switch currently does nothing. I would like to find a device that would fit in that space and act as button. My goal is to trigger an automation anytime the device is pressed. I find plenty of square buttons but nothing that will mount in a standard wall switch space. Or in the alternative a smart switch that can be configured as button to trigger an automation every time it is pressed. Seen lots of Decora smart switches but none that just toggle.
Zooz Zen34
(Z-Wave device)
Works great for me.
You can just disconnect it from AC and instead connect it to the GPIO+GND of a esp. The switch then internally works on 3.3VDC and the thing left you need is a small AC-DC PSU to fit behind the wall switch, something like 
Retrofitting a present wall switch costs only around $5 and has the best possible HA integration possible with local push & native api thank’s to esphome 
This is a $3.50 lolin lite32 board with a buzzer added and beside detecting the switches it works 24-7 as a bluetooth proxy 