This is actually pretty interesting! I'm not a professional historian but I do study this field from time to time

German Americans were actually also put into internment camps during the war, it is rarely looked at because in 1940 the US had 1-1.5 million German people in the US with over triple that with people with at least one German parent. During the war (from what I've read) there were about 10 to maybe 15 thousand Germans interred.

The Japanese Americans are much more known in my opinion because they mainly resided in the West Coast and 120,000 Japanese were interred, which I'm pretty sure while it wasn't everyone was still a giant chunk of the population and left streets full of businesses empty, houses abandoned and a mass forced migration we hadn't seen for decades.

I apologize but I can't answer the Italian Americans part