There was a Nazi party here in the US and a lot of people admired Hitler when he was rebuilding Germany. There were even some members of the press that expressed admiration when they covered the reforms he did.
Privilege can let you get away with a lot of things. There were concentration camps for Japanese-American citizens but none for German or Italian. For the Italians they were asked to persuade their extended families in Italy to stop fighting against us. I'm not sure what was asked for the Germans. My source is from documentaries I've seen (I really like this one).
There was widespread racism directed at Italian Americans that ran for decades. My grandmother's mortgage from 1955 had language referring to Italian America quotas that needed to be referenced so they were not exceeded. That meant the town had to sign off on Italian Americans buying the home.
German is the most common ancestry in America which is likely why we did nothing about German Americans.
From what I learned talking to many WWII vets of German descent, they pretty much all said, "welp our cousins are starting shit again, time to go give them a spanking," and signed up for service in droves even before Pearl Harbor. Lots of Teddy R. fans in that group.