No, it's not appropriate. Momo Yaoyorozu is a character in a story, and creating sexual fanfic about her objectifies her. We should focus on positive aspects like her character development, her role in the story, and her relationships in a non - sexual way.
This kind of fanfic is not suitable. Characters are created to tell a story, have adventures, and show certain values. Sexual fanfic detracts from the essence of the character. Instead, we could explore fanfics that are about her heroics, her friendships, or her growth in a more appropriate and positive manner.
Fanfic involving sexual content is not appropriate, especially when it involves characters like Momo Yaoyorozu from an anime or other media. Such content goes against the respectful portrayal of the character and is not in line with the family - friendly nature of most fandoms.