Siri on the Apple TV has had a somewhat stumbled rollout. The main culprit being Siri needing extra training from different parts of the globe pronounce names being the main culprit. That explanation is all well and good if you happen to live somewhere where that training has happened, and Siri is live on your Apple TV.
Thankfully there is a simple way to enable the new Apple TV’s excellent Siri support but are not in one of the eight supported countries, then you’re not completely out of luck.
Just in case you are wondering Siri is supported in the UK, US, Australia, Canada, Germany, France, Spain or Japan.