Frank Horrigan could be trans considering super mutants lose all sex characteristics in their transformation. Horrigan is so lacking in self awareness that he could literally have forgotten that he used to live as another gender. I don't know the likelyhood of getting trans healthcare in the Imperium, but if it makes a soldier more effective, they might provide testosterone treatment to Cain. Degurechaff is already a gender-swapped character, so we don't even need to stretch the story to make them trans.
Also, none of these characters seem to be heroic in any way. Fascinating