Not really. Apple had to build out the system of entitlements and new APIs for the EU but the segregation goes through the App Store and Developer Program which

Not really. Apple had to build out the system of entitlements and new APIs for the EU but the segregation goes through the App Store and Developer Program which run on policy, not code. It’s not that the EU version of Firefox wouldn’t work on my American iPhone with its American Apple ID, Apple just won’t let Mozilla distribute it to me. There shouldn’t be a problem under the law though. EU laws apply to the EU’s jurisdiction, the EC would have no leg to stand on in telling Apple they have to make all the same changes worldwide just to make Mozilla’s life easier.