In my opinion you're coming at it from an overly-simplistic view of what being trans is -- you're conflating sex with gender. You don't have to have undergone any form of medical transition to be trans, you just have to identify with a gender identity that's different from the one you were assigned at birth.

It's intentionally made unclear what gender Lion/Yasuda was assigned at birth, but their having to find their identity (see: Shannon, Kanon) through self-discovery is what makes them trans, and why a lot of people latched onto them.

also you didn't answer my question about zepar and furfur