Personally identifiable information are IPs, email addresses, street address, name, date of birth, … Lemmy only collect IPs and email addresses. And these are not shared between instances.
Whether the service is hosted in the EU or not, as long as it serves EU users, lemmy should provide a way to delete emails and ip information in a self serving way. (maybe by deleting the account) In the mean time, instances admins have to fulfil requests to delete emails/ips of EU citizens from the database.