If my fiancée is the one inseminated, will I have to adopt the child to be their legal parent?

I came across a gofundme where a trans man was asking for $500 so he could adopt the baby they had via sperm donor. He said it was the only way for him to share guardianship. My fiancée and I are still years away from having children so I haven’t really dug into the logistics of everything. If she’s the one who has our child, would I have to adopt the child for it to also be mine? I assumed that I would automatically have guardianship over it with my fiancée like couples who get pregnant via intercourse. I know in my state, two women are legally able to sign the birth certificate. Is there a way around the adoption? Like if she used my egg? Or would that way make it so she has to adopt it?