I think you underestimate how many US citizens (rightly or wrongly - not going to debate that here) send DNA samples to companies that will tell them their heritage.
SCA is super popular over here (which isn’t always historically accurate, but it often is). Just as an example. My goddaughter’s wife wears a kilt when he’s at sword practice IIRC, and I have a friend who is full-blood Scottish and sits on the board of the local clan group - which has a very extensive membership just in Washington state.
(ETA: Here’s a pretty comprehensive link found with a simple search of Wikipedia - List of works based on Arthurian legends - Wikipedia - not everything is from the US, but a great deam of them are, and those that aren’t are more or less well-known (opera probably less than TV and movies, but I wouldn’t event venture to claim that because of the surprising number of heavy metal bands that use themes from operas around the world.)
Please stop assuming that US citizens are stupid and out of touch with the rest of the world, Henk.