Those Shelly diagrams are confusing because it’s not clear that the diagram is the external connections. I’m used to seeing it the other way-

The SW looks an awful lot like a relay contact that is internally connected to line. Little harm wiring that wrong.

That O terminal looks like a coil that needs a L connection to energize it cause the other side is already connected to N, let’s put some power to it through my switch!

housefire.webp

Here’s how it should be visualized