The "Apple TV" is not a television set; it's a small always-on computer that sits near one. The newer ones include a Thread radio and serve as a border router / gateway for IoT devices to be controlled and automated through Apple Home (usually managed via a user's phone or tablet).

This is not about controlling your smart home. You can do that from your phone, tablet, computer, specific devices like thermostats and switches, voice via Siri, etc.

This is about being able to act as a Matter/Thread hub, which the Apple TV can do regardless of the control mechanism.