Wiring Shelly1 as a single wire 230v Thermostat

Currently I have Shelly1 wired instead of thermostat for testing purposes and all is well. I am ready to move it inside the (gas) boiler and connect existing thermostat as the external switch. I would like a confirmation or two

This is one single 230V wire going out from the boiler to the simple On/Off thermostat, and returning from it back. When Thermostat closes the loop, the heat is on.

I think I should (all connections are inside the boiler):

1) connect outgoing Thermostat wire (now going out from the boiler to the thermosat) to both the thermostat (as it is now) and add the second wire to that terminal and connect it to the Shelly Input port.

2) move the thermostat return wire from the return port of the bolier to the Sw port of the Shelly

3) Connect Shelly Output port to the Return port of the bolier (where Thermostat return wire was connected previously).

Is this correct?

Thanks for the answer! I prefer to check with people in the know I would place a Shelly1 inside the boiler and power it with the only power wires going into the boiler. Actually, the thermostat is on the same clamp as input power, so phase is the same.

I do not understand the "dry-contact" term. Power (3 wires) enter into the boiler. A single 230v wire goes to the thermostat and back from it to the boiler.