Apple TV content per country

I am considering the Apple TV.
The problem is, all the promotions about Apple TV have been very US-centric, so I'm afraid of buying a useless device (I already have a Chromecast).

Is there a matrix that shows which content providers and features are available per country?

To add on to grgarside's answer, you may be able to determine if certain content provider apps are available in your country by using a website that lets you browse the tvOS App Store, such as App Sliced or 148apps. From the app listing, click on it to view the iTunes web listing for it, and it should say it's not available in your country if that's the case.