No it’s nothing to do with Nvidia’s customisations. Essentially there are two systems when it comes to Android TV integrations. The first is one is when the apps provide data directly to the device. This is what the Shield and other Android TV devices use. This enables things like integration with the “Watch Next” row, custom app rows on the home screen and integration into search results on the TV. The apps simply tell Android TV what content they can provide and there is no involvement from an external web service.
The other integration type is integrating with Google directly, not through apps. This is the method used on the Google TV skin. Essentially a content provider supplies their entire catalogue to Google directly, so that it can appear in search results on the Google website, and then in recommendation and searches on Google TV. This means it’s impossible for Plex to integrate with the Google TV, outside of their free movies and TV offering, as there is no way to tell Google about the various different catalogues that each user has (plus the obvious privacy concerns of either Plex or Google knowing what content is in your library). Basically this level of integration is geared exclusively towards streaming services, not services that allow you to have your own local content.
