FWIW, the "Who Will Sacrifice?" text goes from the Murlonios at RI arena stands to one frame of the Matt confessional. While it may be a stretch to think that indicates Matt is the one sacrificing, the religious (not so subtle) sub-text arguably makes Matt the logical choice.
The question is whether the sacrifice is usual CBS hype or not. If so, then BR's option seems the most likely scenario. If sacrifice is not the usual CBS hype, but actually indicates a decision that needs to be made, the question is whether this is one that would be made before the duel is run or after the sacrifice.
I don't like the idea of players sacrificing a shot at Immunity for loved ones. That's huge stakes. Don't think Survivor has ever been that cruel. If they do that, however, it is noteworthy that Natalie is the only one not shown in the challenge.
I toyed with the idea of players sacrificing a shot at the duel for loved ones, but that one seems even worse, since it would dictate that whoever didn't participate would be out of the game. I don't see anyone accepting that offer. Of course, the offer could be made to sacrifice in order to watch videos. No one agrees, so then loved ones appear. Survivor loves to do the reward for sacrifice thing.
If the decision about sacrifice is made after the duel has been won, then the decision might be "do you let everyone view their videos but you don't see yours?" followed by the loved ones appearance. Again, the sacrifice/reward thing.
I do lean towards the sacrifice being linked with Matt in some way since he is shown in that confessional.