Looking for a heating control

I converted all my radiators to use smart TRVs (SONOFF ZHA). The heating has been working well, but the boiler programmer has developed a fault, so I need to replace it. This is a Danfoss FP715 2-channel heating control.

The boiler (and the control) are in a utility room. The current control turns on the central heating or the hot water heating circuits according to the programmed times. It is not a thermostat. My condensing boiler is not a modulating boiler, but the manufacturer states an opentherm controller can be used - I assume these can operate with modulation signals.

I am struggling to find a suitable control that works with HomeAssistant - I’m using ZHA, Matter, and HomeKit integrations mainly.

What I would like to achieve is remote boiler on / off and status. The smart TRV status is sometimes misleading when the radiator valve is open but the boiler is off.

You can see in this TRV chart:

At 12:00 the boiler went off and the TRV remained open - so the solid orange graph shows it as on but cooling down. If I could sense the boiler was off, I could update the TRVs to match.