I had the same search as you. I came to the conclusion that not much are working when you want a sort of budget version.
Take a look below. I’m using a manual thermostat with no intelligence and i’m also using a ESP (2 wires) on my boiler central heater unit.
If you really need a thermostat then this is no option.
If you don’t mind having the thermostat eliminated, than this could work.