Connect Saunier Duval Isofast F35 E H-MOD with HA

I am quite new to HA.

I have installed Sonoff TRVZB Zigbee valves in each of my radiators.

Now I am able to control each radiator independently with HA.

The problem is that I cannot control the boiler from HA. I need this in order to turn all the heating on/off (it’s noisy when it’s on), to increase the water temperature in the heating circuit, etc.

The boiler comes with a remote control, but it is quite archaic, and I want to be able to create automations in HA.

I don’t know exactly which product I need; I suspect it’s some type of relay, but I don’t know which one and I’m not sure which is compatible with my boiler. It can be zigbee (I’ve got the SONOFF iHost hub), wifi or ethernet.

I don’t need a thermostat with a display because I have a tablet with the Home Assistant dashboard, and I’ll control everything from there and my phone.

Can someone help me find the proper product?