Currently I'm stuck in trying to change the focus color of the action buttons in the PlaybackTransportControl using the leanback library. I've tried looking up how this would be possible and looked up how I can override this, but to no avail. If anyone has anyway where I can edit my action button's focus color please let me know.
So I found the answer to this question.. you do need to override a certain file that is giving the focus color of the PlaybackTransport Control Action buttons. If you override the lb_control_button_secondary.xml, that'll help you pick another color for your focus.
Hope this helped anyone else!