I promise I am not a reactionary, but I am somewhat uneducated on the subject so I might say something offensive accidentally, sorry in advance about that.
So, does gender dysphoria stem from a disconnect between the body and some "gender socialization" function of the brain, which could be solved by getting socialized and treated by everyone as the correct gender from the start, or something that stems from a disconnect between the brain and the actual body parts and hormones, so the transition is needed to alleviate that, or both?
Keep in mind that nonbinary doesn't just mean one thing, it's an umbrella. I'm both nonbinary and a woman (I like to say that my internal identity is neither man nor woman but politically I'm a woman).
But yes, despite being nonbinary I still have a lot of physical dysphoria. I need estradiol to not feel like my body is always in a low-grade state of panic, and I feel bottom dysphoria very strongly. But there are people, binary and nonbinary, who have none of those physical feelings of dysphoria and that doesn't change their identities