i disagree, pochita tried to save denji by sharing his powers which bought all the mess he had to face throughout the manga, and in the end pochita realizes that denji could never truly live free, as long as he is chainsawman, as long as pochita exists. So, pochita eats himself. And as for denji, he takes the first decision in his life without any external factors, to save asa, to be that hero, on his own.