> As a perk you retain the functionality of the existing light switch
This sounds super interesting, so both the control from shelly/HA and the physical light switch can be used?
Do you have any pictures/blog/something about how to set that up? I briefly looked into this in the past, but it seemed impossible with the existing wiring (only the live wire is behind the physical switch, no neutral).
Basically the switch becomes a simple boolean input to the Shelly - the actual module is always powered. This allows you to turn it on via the network and turn off at the switch if you wanted to, or completely detach the switch from the actual light and only use it as an input to your home automation controller (maybe you want to use it to toggle a different light than the one it's connected to?).
For no-neutral operation they sell bypass resistors that you can put in parallel with your light to pass through enough current to keep the Shelly powered on.