TVNZ has an app on select Android TVs (including Sony and TCL), that run Android OS 5.1 and above.
You can find and download the app by visiting the Google Play Store. Your TV will need to be connected to the internet and running a recent one of the latest operating systems.
Note: The latest Sony Smart TVs usually come with Android TV. You just need to open the Google Play Store on your TV and search for TVNZ. For the best experience, you’ll need to be running the latest software.