I have 16 UFH zones on both floors, I thought long and hard about replacing the old analogue thermostats in each room with temp sensors and a 8 chamnel relay to control each manifold, pump and boiler. But actually all I needed to do was update what I already have, I have replaced the old thermostats with a sonoff basic with a dht11 attached. Im using a simple rule to turn the thermostats on and off depending on the set point and now I use Alexa to turn them on and off or up and down with routines.
Its all very simple and works a perfectly.