Gender identity doesn't get assigned at birth. There is no "gender" field on a birth certificate.

Sex gets identified at birth (at the latest, usually before, during pregnancy, unless specifically requested to keep it secret).

Two reasons this is important to point out:

• Assignment implies that the act of assigning is what makes it so. It's not. If a doctor says that a male baby is female, it's not now female just because they said so. "Identify" is a much more accurate description of what the doctor is doing.
• The whole premise of "transness" being a thing relies on the notion of sex and gender being two distinct, independently-variable traits. So be careful not to conflate them. It causes needless confusion, since conflating them literally undermines the whole thing--after all, if "sex" and "gender" are equivalent, then it's objectively impossible to be trans.

I never claimed to be an expert. I am admitting now that I am somewhat ignorant as to what the exact definitions are, but from what I understand from what my NB friend explained it is that if you transition from one gender to another that makes you trans. NB are neither gender so there was no transition between genders.

I guess one could make the argument that they transitioned from being gender-labeled to being non-gender, but IMO that's a stretch in an attempt to label NB people as trans.

That being said, there is nothing wrong with being trans. I was just trying to make a distinction as was explained to me by a NB person.