I could see Garleans being added after next expansion where they may become a more neutral presence for us. Older stories might be weird playing as a Garlean but you'd have to figure maybe your adventurer has something going on that prevents them from being loyal to the empire. IDK.

The purebloods are just Elezen with round ears so do that and make them another clan of hyur (the clan system could be expanded I think without adding entirely new races).