I think for me, I think of possible endings as "How many unique ways are there to conclude the main narrative?" An origin companion that isn't required might have an "ending", but I consider that flavour to the ending. It's like with Final Fantasy VI, it's a completely linear game with a single ending, but you can technically have a bit of flavour added to the ending if you rescue certain people/recruit other companions/etc.
this "We don't know how many endings we have" thing seems extreme exaggeration/marketing.
