Not following your point here “N/O means if no power no connection, so you need to read the instructions, or use a meter”
But reason for posting is the black neutral wire threw me a bit (was expecting blue), and also Meross support telling me to wire that (Black) into Live of the new smart...
Attached photos of current wall thermostat which I think should be compatible. Has live, neutral and a control wire all feeding from the central heating / boiler wiring.
From the wiring diagram on the existing Myson
MRT1 it should map over as 1 (Brown) live 4 (Black) neutral and 3 (Grey)...