The Boku no Hero manga is finished. It reached its conclusion after a successful run, leaving fans with a complete narrative and memories of an exciting journey.
Well, there's this fanfic called 'Bakugou and the Lost Quirk'. In it, Bakugou loses his quirk and has to find a way to get it back while dealing with his own self - doubt. It's a really interesting take on his character. Also, 'Bakugou's Secret Training' is quite popular. It shows him training in secret to surprise everyone with his new skills.
You could search on platforms like Viz Media or Crunchyroll. They often have a wide range of manga available for reading. Just be cautious of unofficial sites as they might have copyright issues and poor quality scans.
One popular idea could be creating an alternate origin story for a character. For example, giving Deku a different quirk acquisition experience that still leads to his growth as a hero.
It could be Midoriya. Imagine Midoriya getting access to Iron Man's technology. He's already a determined and intelligent hero - in - training, and with Iron Man's tech, he could become even more powerful. He might struggle at first to adapt to the new technology, but his strong will would drive him to master it and use it to protect others in new and exciting ways.
One great 'Boku no Hero Academia Izuku' fanfic could be one where Izuku discovers a new, hidden quirk within himself that's not related to One For All. This could lead to him having to train in a completely different way and form new relationships with his classmates as they all try to figure out this new aspect of his powers.