Brand new to Home Automation and HE. Caught Patrick on Home Gadget Geek podcast. Bought the hub shortly after. Built my zigbee mesh network first thing using several switches then added in a few motion sensors, a couple Sengled bulbs, adding a couple door sensors next. Would like to add a zigbee thermostat. I'd like to have the option of controlling it with Google Voice. Would I be able to do this with the zigbee Zen Thermostat? Any better options/suggestions?
Yes, Hubitat's Goolge Home integration supports control of thermostats (the Alexa integration does not). Hubitat extracts details about the device--the exact model, underlying protocol, etc.--away from you (for the most part) and apps (including integrations like the GH one), so beyond that, a Zen Thermostat should work just as well as any other.
...or at least as well as it ever works. Mine consistently reports weird setpoints, like I'll set it to 60 and it will set itself to 59.9 or 60.1. It's something I've learned to live with. It's cheap, doesn't look ugly, and more or less does what I want, so I don't have any problems here. Just something to keep in mind with this device (which did the same thing to me on SmartThings, so I'd say this is just how the device behaves).
EDIT: I assume you mean voice control with Google Home/Assistant, not Google Voice (which is a telephony service). I do not know of a way to control anything via Google Voice or why you would want to, but I'm sure there's some hook you could use (does IFTTT support incoming calls?).