Not sure about NBA, but there's an official UFC app in the play store
joften
UFC app for Shield TV is garbage. Heads up. Search doesn't work correctly (example...I'll put in UFC 17 and get back 171,172,etc but not UFC 17) and the fast forward/rewind are garbage. They only let you go back and forth in 1 min increments.
Not sure about NBA, but there's an official UFC app in the play store