OK. I give up. I've found out everything I want to know about the Channels Android TV version except where I can actually get the FRIKKIN' APK to sideload.
Maddening.
I know there were issues a couple of months ago where they had to remove the simple install from the stable version's settings, but I never thought I'd spend an hour looking for the APK for my new Shield Pro (warranty replaced after ethernet port died).
So, someone please link me to the Android TV client Beta APK please.