Fortunately, when I was in high school (1999-2003), guys didn't get naked in the locker room before and after PE.
I don't know what the girls did, because this was years before my transition, but in the guys' locker room, nobody ever took off their underwear. We all swapped our regular clothes and our gym clothes out while leaving our boxers in place. We didn't shower, either, which is something the article mentions in passing (with a link to a more detailed article on the subject).
The only time I ever saw people naked (as much as I tried not to) was on the rare occasions we'd go swimming for gym class.
Many years later my sister became a teacher and her main complaint about teaching was "the kids stink."
In retrospect I have no idea how bad I smelled after running several miles or playing kickball and then not showering because it was just not done by anybody in gym. The stigma of showering among peers was great enough that nobody seemed to care, although this may be more a symptom of a general lack of self-awareness among kids that age.
What do you mean, 'fortunately'?. Not only is it disgusting from a hygiene point of view -- especially wrt sweaty teenagers! -- it's also a great way to come to terms with nudity. With porn as the main source of nudity, it's no wonder that so many teens have self-image issues.
I think the 'fortunately' was in reference to OP saying she was pre-transition, which I imagine might make a men's locker room experience anxious and painful, and I thank OP for bringing up that perspective because I hadn't considered it while thinking about my own locker room experiences.
I agree with you that showering after wrestling practice forced me to come to terms with nudity, and I'm grateful for the confidence boost that comes from seeing that most men look the same under their clothes. (But I don't think "size anxiety", if you will, is limited to special snowflake Millennials who haven't been naked in front of others... it seems like many men of all ages worry about it and feed into a thriving industry of enlargement scams -- at least judging by the contents of my spam folder!)
Exact same years as you, the girls never fully undressed either at my HS. Some of the more bullied would try to change in the bathroom, but our PE teacher shut that down really quick for some reason.
I don't know what the girls did, because this was years before my transition, but in the guys' locker room, nobody ever took off their underwear. We all swapped our regular clothes and our gym clothes out while leaving our boxers in place. We didn't shower, either, which is something the article mentions in passing (with a link to a more detailed article on the subject).
The only time I ever saw people naked (as much as I tried not to) was on the rare occasions we'd go swimming for gym class.