Smart radiator thermostats and zigbee2mqtt

I currently use Honeywell Evohome radiator thermostats, but due to poor reliability I am looking to change to a zigbee2mqtt based solution (no cloud dependency). Is it just the zigbee gateway that must support zigbee2mqtt or the radiator valves themselves?

Any recommendation for reliable zigbee valves which work with mqtt and an app, which are readily available in the UK would also be very welcome.

The valves do too - see the list at Zigbee2MQTT - there are lots to choose from. I’ve been dipping my toes in the water and currently have 1 Tuya and 1 Schneider valve. Obviously Z2M does MQTT but I’m not sure what you mean by ‘app’ ? The app here would really be HA companion app.

Hi Tim,
I looked through the list and could not find a single one which exposes a reasonable number of attributes AND is available in the UK from a UK based supplier !
The other question I have, is does the Tuya App, which seems to be the most commonly supported gateway, support switching on the boiler when (and only when) there is at least one radiator calling for heat?

I’ve got this one :

and a Tuya TS0601 (didn’t buy that one - bought it on ebay) but it looks exactly the same, lots of companies seem to re-brand Tuya)

The Tuya exposes a lot more entities but I’m not sure I’ll use them all (holiday mode for example) The Schneider doesn’t expose the battery level by default I needed to create a template sensor for it.

I’ve never used the Tuya app sorry. Nor do I have a heat on demand set up (Although I assume you could construct that with some HA automations - to tell the Hive to turn on the boiler when one of the rads temp falls below X degrees etc)

Thanks for the replies. I have another requirement I am trying to meet.
My current Honeywell Evohome provides heat on demand functionality, switching on the boiler if (and only if) one of the smart radiator stats are calling for heat.
I know I can build automations to operate a switch to turn the boiler on through HA when a stat calls for heat HOWEVER, I need to provide for the situation where HA fails for some reason and I am not around to fix it. SO, I would like a solution which will call for heat without using HA, so the heating will continue to operate and can be controlled/reconfigured via an app until HA is back and all without use of a cloud service!
Any suggestions?