does anyone know the drover's real name? they don't mention it in the movie.

No sorry :(
but I do know that he wanted to be called 'The Drover' because of something to do with his past. I looked up on Google but couldn't find much stuff about it. Maybe it's suppose to be a twist?

His name is Ben... it's 発言しました in the beginning bar scene when Margarry calls him from the door, and Ivan tells him "no boons in here".