Seeing that we have few minor nation weapons already in the tech tree, maybe DF can just allow us to change the nationality of the squad from preset rooster for lets say 5000 silvers.
For example if you want to change Allied AT I team from British to American you can pay 5000 silvers. The dev can decide which squad will represent what nationality from (maybe) some of the legacy squads rooster or create a new one (all they need to make is a little bit of lore, name, and the insignias).