GDPR compliance seems pretty all-or-nothing. It wouldn't be sane to respond to a "hello, are you complying with GDPR for my data" letter with "You aren't a Euro

GDPR compliance seems pretty all-or-nothing. It wouldn't be sane to respond to a "hello, are you complying with GDPR for my data" letter with "You aren't a European citizen so we don't have to". If you're wrong, you get screwed over. The only sane options IMHO is either set things up to be GDPR compliant or to have zero business presence in Europe and tell them to pound sand.