Tommy will eventually gain Elytrian powers by going to the End Cities
Judging by the fact that Ranboo was allowed to enter the stronghold without any interference, the End isn't off limits to members of the server. Potentially, this means that as part of Tommy's quest to become an Elytrain like Phil, they could resort to going to the End and killing the Ender Dragon to access the End Cities and getting a physical Elytra instead of training Tommy to grow wings naturally.Tommy is a fledgling Elytrian, but he still won't be able to fly
Going off the description of their respective origins, it is mentioned that Avians LOST their ability to fly. Maybe Tommy was considered an Avian because something happened to his wings that prevents him from flying.