The ShieldTV has all the same accessibility features as any other Android device, including talkback.. I'm finding all sorts of posts about people accidentally enabling it and how to turn it back off again.
It turned on by itself once and let me just tell you how annoying it was in those few moves to get to settings.
Edit :I guess it worked well.
It's Nvidia shield, not envideo...
source: https://support.google.com/androidtv/answer/6123320?hl=en