Of course Apple has more SKUs than they need to have. Different product generations, sizes, storage options, colors, etc. Adding a different connector on some subset of models for some number of countries is perfectly doable.
It's probably moot because Apple seems to be moving to USB-C over all their product lines anyway. But if the EU were to mandate something that Apple felt was a materially inferior choice, I'd fully expect them to comply where they had to and implement a different option everywhere else.
GDPR is simply a case of, if a company doesn't have a compelling reason for not following GDPR where possible, it's just easier to follow mostly uniform rules worldwide.