And for a Ben final line…
Oh! Or what if he calls out to her right before she sees him and gives him the lightsaber? (“Rey…”) Not super deep, perhaps; but conceptually, I think it would flow well.
I feel like this is the one that would work best. Though I’m sure someone could easily find some Sad Adam Driver Noises in Marriage Story if they wanted to add that to the bit where they take turns dying.