Pretty much this^^^^^^^It could be the reason why we haven't seen his face since meeting the sage.
What are you talking about? Sasuke has Indra's chakra in himself, and you need the Sage of the Six Paths' chakra to awaken to Rinnegan, not Indra and Ashura's. When you combine their chakra, you get power like the Sage, that's why you can achieve the Rinnegan. Hagoromo gave his chakra himself to Sasuke.Sasuke isnt getting the rinnegan.
The rinnegan belongs to Rikudou. You need Indra and Asura chakra to awaken the rinnegan. Sasuke has neither of this.