RE: dude with ovotesticular dsd. It is a real dsd. It used to be called true hermaphroditism, because they do have at least some of each sets of reproductive organs. Including a small version of a uterus, and one of each gonad, and a penis. Individuals are typically sterile, but apparently some of them do produce sperm and/eggs.
This guy is reported to have both a menstrual period and erections.
Another website on rare diseases says there are at least 500 people who have been diagnosed with this dsd. It goes on to talk about how it's diagnosed, with genetic tests, mris, pelvic exams, etc. A lot of these people have gender assignment surgery as infants based on their external genitals.
This troon might actually be telling the truth. It's very, very unlikely but possible. His story is consistent over time, which you would not expect from a larper. I do remember him saying he never got officially diagnosed though, which does lend credence to being a larp. It seems like getting erections and a period would be something his parents would have investigated as a teenager. On the other hand he says he developed cysts on his testicle but not his ovary, which would have caused him to be diagnosed.
End result: possible but not likely. I'm fine with assuming it's a larp, but the disorder does exist and does present with his symptoms. There's just a tiny number of people with this disorder though, that the odds of running into one of them on reddit is astronomical.
Gibs me those rainbows.