I read the "shall implement an interoperability solution that...in a way that is equally effective as the solution available to Apple." a bit differently. Apple must ensure interoperability, but they are allowed to implement a separate solution to Apple's internal one if they feel it is better to do so.

So far it seems like a lot of the requirements could be satisfied by Apple just opening their APIs given that an identical solution would in fact be equally effective. The EU could have mandated that the solutions be identical but that would be more restrictive to Apple despite the requirement seeming like it would be less work.