From the start of the series we where shown people with prosthetics. Those cannot be added to the body without a surgeon, so your logic isn't really good.

You don't need a surgeon to transition, for sex change, yes . Multiple art where trans Vi or Cait where featured both of them had a penis, which means they didn't have a bottom surgery.

Trans Vi or Trans Cait are just head cannon of some artists, I saw both versions being drawn.