A heal to die on
In the final moments of Ben Solo's life, Darth Sidious siphons the force through Rey and Ben to rejuvenate himself and empower himself to new evil heights. Rey and Ben fall to the ground after being drained. I'm told in the final version of the film, Ben Solo realizes Rey has taught him the power of compassion. Ben then uses the power Rey used on him to heal the woman who healed who did the same for him earlier. Ben does so knowing that Darth Sidious will destroy him for it. But that action will allow her to rise. Ben heals Rey and the Sidious pushes him into the abyss of Exegol for it.
While the Emperor zaps his Sith lightning into the sky above Exegol, Ben heals Rey. Anakin, Luke, Yoda, Obi-Wan, Ahsoka, Ezra, and Leia tell her to "rise" and she does. Rey pulls out the concealed Leia saber and makes an "X" with the blades to deflect Darth Sidious' lightning blast and the power is volleyed back to the Sith Lord destroying him.
Ben Solo's selfless sacrifice
Ben's last act is a compassionate one to save Rey and the universe. He consciously makes a smart move knowing he will be lost in the exchange but the good side will win the game. He acts completely selflessly. Han Solo gave his life for his son, knowing his son was inherently good and it would be the right thing for the universe. Ben's compassion and love for Rey is expressed not with a kiss but a sacrifice proving Han Solo right.
Ben is redeemed and the galaxy is saved. Rey destroys Darth Sidious thanks to Ben Solo's final act of compassion, like his grandfather did for his uncle the generation before.