Okay so a couple things!
First off, there's currently a character popularity poll being run by the SD discord, so be sure to vote for your favorite if you're into that kind of thing! XD

And about the comic: whether trans magical girls are a thing is legit the #1 questions I get asked about SD. I've been happy to respond to the affirmative in private, but I didn't want to make any kind of post about it until it was in the comic itself. But yes, it's definitely a thing! No, I will not be fielding any specific questions about the physicality of it.
While we're on the subject, since this has also been asked quite a bit: I don't plan to have NB magical girls in the comic, just because there's such a complexity to the ways that can present, and I don't want to give anyone the impression that I think "This Is How I Think It Would Work, For All NB people." That said, I also wouldn't say it's not possible within the rules of the world! There's lots of valid ways to imagine how a system where "anyone who's a girl can be a magical girl" works with NB, but that's not really my place to adjudicate, I think.
I hope that all makes sense!!