Received the Apple Lightning to Digital AV Adapter yesterday.
Good news! It successfully mirrors the AT&T Watch TV app to our TV's HDMI port. It works with Discovery Ch., HGTV, etc. using cellular and wifi data (our cell plan includes unlimited viewing of AT&T Watch TV using cellular data for free---no caps). Being able to use cellular data is a huge plus while we're on the road with no access to wifi. As long as we have a strong 4G or LTE signal (and this adapter) we can mirror unlimited AT&T Watch TV using the TV in our camper.
FWIW, it also mirrors Hulu via wifi. Didn't try Prime Video, but have no reason to believe it wouldn't work, too.
This adapter definitely wasn't on our radar as an option. Thanks to everyone for your help!
