what about for shield tv?

i downloaded the Android O rom for the nexus player here few days ago: https://developer.android.com/preview/download.html extracted the system.img I was hoping to get a newer youtube leanback build but as per testing its the same one i have.. leanback launcher apk will not work with the mi box.

Buy a nexus player and sign up for the beta. Available at Walmart. https://www.google.com/search?q=nexus-player+buy+%7C+shop+%7C+price&oq=nexus-player+buy+%7C+shop+%7C+price

You can use Android Studio 3 preview and run a simulator to play around: https://developer.android.com/studio/preview/index.html

You can just enroll in the beta and you'll have it