Hi All:
I was able to hide Sling app, and stop it (mostly) from auto-booting, thought I would share:
ADB Shell ->" pm disable-user --user 0 com.sling.airtvmini"
I then downloaded Launch on Boot and selected an App (Plex) to start, becuase otherwise it shows the Sling Splash Screen, and appears to freeze looking for the app to launch, launch on boot worked to by pass it (did not work w/o disabling the app above).
If anyone has a way to just launch into the home screen instead of app, that would be appreciated.
I don't have the answer but just wanted to say well done already !