Probably only going for TRVs on half of the radiators so will still need something to control the rest.
Yes, thermostat isn't quite right. A lot of the smart thermostats are wireless and battery powered but have some form of link/hub which wires into that spot where the thermostat was.
If you're going with smart TRVs, you probably don't even need a thermostat.
As it is, and afaik, most smart thermostats are battery powered in any case.