I agree. The zone valve motors are controlled, and also powered, by the 24 volt system so it should be a matter of pigtailing in to the common return where it connects to the valve wiring. As I’m learning, the zone valve itself is already wired to the boiler and that connection controls when the boiler circulator motor runs. So we shouldn’t have to mess around with that part at all. Or touch the boiler itself.
When we get those thermostats I’ll take pictures and post how it went.