Apple announced during the WWDC 2021 keynote that it would add third-party support for Siri. One of those devices to get access to the virtual assistant is from Toronto-based company Ecobee. Later this year, the SmartThermostat with voice control will get the feature through a firmware update. You will need a HomePod or HomePod mini to get Siri to work with your device, though. But, if you've been looking for that integration, it's arriving soon.
Source: Apple Insider