Technically, it's German free-TV. They are broadcasting for Austria and Switzerland as well, it's the same language, after all. The big networks even offer Austrian and Swiss versions of their channels, but that's first and foremost about providing commercials for the specific countries, so that they can collect more ad money. Occasionally the news are their own thing too.
Makes sense American Football is somewhat popular in Germany when NFL Europe was still arround the Frankfurt Galaxy always had pretty good attendance plus there are semi pro leagues in Germany. Speaking of NFL Europe they kinda gave up on that a bit too early.