Black Panther and Ant-Man only allied with their respective Avengers sides, but never got a official Avengers employment like Spider-Man did during Infinity War. Currently, they aren't Avengers.

I don't think T'Challa is based on this wiki. They never list him as one. The Black Panther dvd cover does say "His future as an Avenger" so idk. I think he'll focus more on being a king, and then help the Avengers as needed.