I think that Rey looking over her shoulder, Ben walking up (as we have in Pasana) and then the VXF of the twin suns behind him would be absolutely gorgeous. Ben showed up on Exegol on his own, we don’t have to see him leave there. I had actually imagined something for my own edit down the road where during the celebration, after Rey hugs Poe/Finn, there’s a slow reverse of the hug and then a serious look at them with some dialogue (probably VO’d with the angle on Finn and Poe) from elsewhere that roughly has her saying: I have to tell you something.

So that covers them knowing about Ben.

The group on the Falcon
Rey buries the lightsabers
Rey looks over her shoulder
Ben walks up, silhouetted against twin suns
Falcon takes off

Viewers can assume that Ben joined them or that he left on his own and he and Rey just had a talk. It’s ambiguous, depending on preference. Still, voila, #kylolives!