This proves two things. First, the fact that grandma, a trusted and authoritative figure, presented a new idea and the child immediately tried to copy it proves that the child has no clue what he's talking about. This is just like religious indoctrination and is not a choice conciously made by the child. Second, the fact that the daughter wants to be nonbinary simply because "gender hasn't done anything for her" proves that nonbinary people just take a thing literally everyone in the first world does - ignoring "gender" while recognizing sex - and acting like they're special for it. Gender hasn't done anything for me, but I am a biological male and thus will use he/him/his pronouns and the men's restroom. I don't go around as a walking stereotype, in fact I often defy and detest stereotypes, but I am capable of nuance and so can reject the masculine stereotypes without rejecting manhood altogether.

They're so simpleminded and narcissistic that they think it is impossible for someone to identify with their sex without being a walking stereotype and also think that they're the only ones to figure out that they can differ from the stereotypes of their sex. They honestly think they're better than us because they figured out that being a housewife isn't something they want to do but then couldn't figure out that they could be a woman without being a housewife.