Unless FB seizes to have offices in the EU and stops having an HQ in the EU and also stops doing monitoring of people in the EU and also stops any regular service for people in the EU, the GDPR has teeth and people in the EU can ask facebook to send them all data they have, then ask them to delete it and revoke any future permission to process their data.

Since the GDPR covers people in the EU that means if you're in the US you can take a vacation to Italy or France or Germany and then pull that stunt on Facebook. (technically)