In fact, Snowball is purely a work of imagination. It was crafted by the author's creativity and doesn't draw from any true incidents or real-life characters.
Chainsaw Man follows Denji as he navigates a dangerous world where devils exist. His life changes when he becomes part-devil and has to deal with powerful foes. The story has exciting fights and explores themes like friendship and survival.
There is a Chainsaw Man light novel. It offers new perspectives and adventures within the Chainsaw Man universe. It's worth checking out if you're a fan of the series.