Well, in such a fanfiction, there could be various hints. Maybe Zoro's behavior might be more in line with typical female characteristics described in that specific fictional world, like being more empathetic or having different social interactions compared to the original male - character version. But it really depends on how the author has crafted the story.
As of the latest chapters, Big Mom did die. The circumstances surrounding her death were quite complex and tied to a series of intense battles and plot developments.
There could be a 'big boobs mom' who is an advocate for plus - size moms. She might start a support group where moms can share their experiences, not just related to body image but also parenting. Through her leadership, she helps other moms feel more confident and less alone, which is a very positive story about using one's identity to bring about positive change in the community.