Ecobee's SmartThermostat with Voice Control has a built-in Alexa speaker and already supports Apple HomeKit as well as Google Assistant if you have a separate compatible smart speaker or display. This update is designed to expand Ecobee's existing HomeKit integrations by adding built-in Siri capabilities.
The thermostat company says folks with a SmartThermostat with Voice Control who also have either a HomePod or a HomePod Mini can speak to Siri from their smart thermostat using a standard "Hey, Siri" command. This update is supposed to work on both existing and new SmartThermostats with Voice Control.
It's less than ideal that you need an Apple smart speaker for the built-in Siri portion to work. But, as always, we'll test it out to see if the update adds any value to the SmartThermostat with Voice Control.