Honestly, I think this may be a school-specific thing. I feel like some people refer to people in the LGBTQIA+ community as underrepresented in medicine, but I'm not on an adcom.
But I can more concretely talk about my experience applying. On my app I identified as genderqueer and transfeminine and had a lot of ECs that were related to serving the LGBT community, especially the trans* community. This was a consistent theme throughout my entire application, and I feel like it is going over well ( 5 II, 1W (at a school that waitlists most applicants post-interview), 1 A, 1 Post-interview R). It's also been a topic I've brought up in most of my interviews, including the school I have an acceptance.
Basically, I think it can be worth mentioning if the rest of your application aligns with it. Feel free to PM me if you want to talk about it more.
I wish you all the luck in the world on your application cycle! We need more trans doctors!