She is 100% of the female sex because in the past she had posted pictures of herself which people have seen (myself included) + live concert reports have confirmed this as well
As for gender I don't think she has specified anything. For the record I have never hear of her asking to be identified as male. I just know that in the past she asked people not be too concerned about it (her gender) because I believe that she didn't want to be judged by it.
Well there was also many instances where people fought about her gender...
Like some people felt betrayed she wasn't actually male??
I saw things back then lol....
Whenever NaNo was still going under the YT username RougeRogue, the user was known to self identify as male, which is a big part of the reason why all of that content has been removed.
I believe no matter what gender Nano identifies as, there'll always be fans by her side <3