Germany’s Reichsbürger are not a coherent movement - there are several competing Reich governments each issuing their own ID cards, driving licenses etc; some say the legitimate German state ended in 1918, most say it ended in 1945, some say it ended in 1990 with reunification and some say the state is a corporation they refuse to do business with - sound familiar?
What the fringe on flags is to sovereign citizens, is different numbers or feathers on the German armorial eagle on official documents to Reichsbürger.
They have been treated as a nuisance before but that’s going to change. A dead cop is a big deal in Germany (see the graph on page 4 of this PDF - red bars are police officers killed by criminals, blue bars are people killed by police officers, the statistics for 2016 on that graph are obviously out of date.)