I'll laugh if we are all speculating about a region based on France and a different country is used instead. Anyway, if it is based on France, maybe as a post game location you could head to a nearby town in what would be Poland in real life. In the town could be a pokemon world take on a concentration camp. I know it may be controversial, but think about how cool it would be. Maybe it could be the cemetary area for the game, like Lavender Tower or Celestial Tower.
You think concentration camps are cool?