The last story in Buster Scruggs has no one fixed meaning. It could be seen as a reflection on human nature, or a metaphor for the journey of life with all its uncertainties and surprises.
I don't know for sure as it's a fanfiction. It could be Naruto himself using the mega buster. Or it could be a new character created specifically for this story.
Love and friendship are often explored. It could be a slow - burn romance where they overcome obstacles to be together, or a strong platonic bond that helps them through tough times. Another theme could be redemption. Maybe one of them has a troubled past and the other helps them find a new path. For example, if Buster has made mistakes in his past, Angel could be the one to guide him towards a better future.
Well, in the last story of 'The Ballad of Buster Scruggs', it's a deep exploration of mortality. The events that unfold seem to be a commentary on how fragile human life is. The setting and the events are so well - crafted that it draws the viewer or reader into a world where death is always lurking around the corner. It also shows the different ways people react when faced with their own mortality.
Another possible theme is growth. The characters, Buster, Taylor, and even the worm, might experience personal growth throughout the fanfic. For instance, they could learn important life lessons from their interactions with each other. This growth can add depth to the story and make it more engaging for the readers.