On the receiving end of this controller, there’s probably just a relay shorting 2 wires from the boiler together - like the Honeywell BDR91.
So, you could just replace that by some Shelly switch and wouldn’t have to use the proprietary radio protocol.
On a sidenote: Those room controllers usually “learn” how long it takes to reach the target temperature (as this can be vastly different between summer and winter) and move the starting time accordingly. So they reach the target temperature at the programmed time. At least the more expensive ones do. You’d have to do something similar in your automation if you want that comfort. (Unless HA already has some code for that…)
This assumes as a tenant you have physical access to the boiler room. From the video, it seems like this person might have that access, but not everyone might.
Unless you share the boiler’s output with someone, I’d be surprised if you didn’t have access.
But still, if you don’t want to mess with the electrical connections, manipulating the radio waves works just fine. :)
Fun read! I’d like to do something similar if I had any control over my apartments heating at all… Sadly it is all just manual valves on the radiators.
There are smart valves. You can just unscrew/unclip the existing dumb ones and replace them with smart ones. They usually even report the temperature (well, near the radiator - so you might want to get extra temp sensors for the other end of the room).