If you're going with smart TRVs, I'd be getting the appropriate controller - you'll already have the bridge etc., so why face the hassle of trying to integrate it all.
Does your hot water come off the boiler too? (In which case controller > smart switch.)
We have oil central heating in our house, boiler is outside and we switch it on/off with this switch/timer.
I was hoping to replace this with some form of smart switch, and control each room temperature with smart TRV’s.
Has anyone else replaced this sort of switch? Do I need a smart thermostat, or would a smart switch or relay suffice?