One interesting Undead Unluck fanfic could be those that explore the backstories of the characters in more detail. For example, a fanfic might focus on the origin of Fuuko's unluck ability and how it has affected her life from a young age. It could show her experiences in school or with her family that we haven't seen in the original work.
The ending point of the Undead Unluck anime in the manga can be quite variable. Sometimes, the anime might stop before reaching a major manga storyline or might consolidate certain elements. It really varies based on the production choices.
Another way is to join Undead Unluck fan communities on social media platforms like Reddit or Discord. Fans often share and recommend their favorite fanfics in these groups. You can ask for recommendations, and they'll be happy to point you to some great ones.
Barefoot Billy in the 'barefoot billy true story' might be a unique individual. He could be a person who rejected the norms of wearing shoes. Maybe he had a philosophical reason for it, like believing that being barefoot kept him more in touch with the real world. Or perhaps he grew up in a situation where shoes were a luxury he couldn't afford, and over time, it became a part of his identity.
Sure, Billy Bathgate is fiction. It falls within the realm of creative writing, where the author weaves a tale that may or may not have any resemblance to reality.