Exposing advanced heating control as a thermostat via HomeKit

[florisre]

I have a room where I want to control the radiator valve via AHC. I was thinking to have a numeric input for the comfort temperature and a switch as a presence drop-in, also a person based on wifi connection to a specific device.

I would now like to expose the input and the switch as a HomeKit thermostat, such that the comfort temperature and whether to use comfort or eco temperature can be controlled intuitively on Apple devices. How do I go about doing that?