If you just want to copy the set point then this post will be helpful:
However it seems you also want to use an external temperature sensor?
That works, in my opinion generic thermostat is fine for that.
It becomes a bit more challenging, but for now I don’t think I have enough information to be sure I give you the correct code or suggestions.
You need to post more detailed what you have and how you want it.
Underfloor heating. Here is a thread with lots of information.
Underfloor heating with zone control - Share your Projects! - Home Assistant Community