Which devices can use the voice functionality?

The voice functionality is available for a device that is running the Google TV operating system. A good example of this would be the Google Chromecast 4K or the Nvidia Shield. It is also possible to use it on TVs that run the Google TV operating system, for example new TCL or Sony TVs. To set up one of these devices, follow the Add a Device feature on the App and select Streaming Device and then Google TV.