I’m looking at this relay to smart enable some manually operated switches. I thought about just replacing the switches but my wife is resistant to any change.

The ZBMINI-L2 claims that it can fit inside the standard junction box, (here in the US it’s the 120 type) along with the switch. I opened up a few boxes and between the switch and wires, there is hardly any free space.

So am I understanding this correctly? Do they really expect you to pack everything into the junction box?