I’m a genuine American mishmash of generic white people who came to North America starting in 1620 and ending in the 1920’s with my last immigrant ancestors being processed through Ellis Island. There’s been a lot of assimilation and a little bit of holding on - my family does have a few practices that have been preserved from the “old country” but it is very easy to commodify them and make them a gimmick, such as Scottish-Americans who wear kilts but don’t care to study the history of Scotland or how Scottish people evolved as a unique culture that was both Celtic and Germanic and multilingual. Also, some immigrant cultures have maintained some levels of independence and even became independent to some extent from both their ancestral homeland and the rest of the US, such as the Pennsylvania Dutch. Being Penna Dutch is not the same thing as being an American of German ancestry - being born in Philadelphia to a German WW2 war-bride who came back with your dad doesn’t count.