It’s has a ZigBee radio and will connect directly to the SmartThings hub. No 3rd-party or cloud-to-cloud integrations necessary. It joins and shows up as a thermostat in the ST app.
I have two. One downstairs (from Best Buy). One upstairs (from e-bay). they work with Smartthings, Alexa, and Me. FYI, I believe the Pearl thermostat was the thermostat of choice in the Smartthings Smart Home.