One more observation:
Over here, we tend to mock people who wear "wrong" jerseys to a particular game. Think of the random Chiefs jersey spotted at the Panthers training camp, or a Dallas fan showing up to a PIT-BAL game
In Europe, the fans of (whatever team) are happy to be surrounded by other NFL fans, and happy to attend any NFL game at all, no matter who's playing. We saw jerseys from pretty much every other team present around town and at the stadium
Because they have so few opportunities to cheer their own team live in person, they take every opportunity to celebrate NFL in general, even if it means wearing "the wrong" jersey for an international game. Those fans are excited just to watch football, no matter who is playing