If you want to determine the country in which your App is being displayed, you could use common methods that are being used in the common web. Examples of these methods are: determination by IP address, determination by credit card information.
The Smart TV platforms give back the property "Accept-Language" in the HTTP header with a possible country sub-tag, but you should not use this to determine the country: this property is purely meant to determine the language of the Smart TV platform interface (it could be English for a Smart TV platform used in The Netherlands).