This app was mentioned in 2 comments, with an average of 1.50 upvotes
Hmm you could use Anytime Gallery For Wear and pre-load it with pictures you think he would enjoy or maybe with Video For Android Wear he can watch some videos of Elmo but you have to speak out loud what you are searching for though or you could even try this Little TV for AW for funny gifs and stuff. Here is also a classic Invaders game that is easy to play as you just tap the screen to shoot while it automatically moves left and right.
I personally use one called 'Anytime Gallery for Wear'. It lets you choose a local folder to sync to your watch.