Chapotraphouse

I think Reichsbürgers are a slightly closer comparison. Their primary gripe is the illegitimate succession of states. North American SovCits and "Freemen on the land" are completely divorced from reality and their beliefs hold more in common with flat earther types and other conspiracy theory nuts.

That's not to say Reichsbürgers or SSSR/Soviet Legalists are in touch with reality, but they're not typically on the same level of woowoo as the dudes who think "traveling" in the driver's seat of a car somehow is distinct from driving or that fringes on a flag displayed anywhere in or near a courthouse means that it's a maritime court.