I don't know what gave you the idea that Apple is supposed to offer any kind of functionality on Android. If they don't want to sell their AirPods to Android users, I don't have a problem with that (or vice versa if Samsung doesn't want to offer their buds for iOS).
My point is that there needs to be a more level playing field between competitors and the platform providers on the platform they do control.
Garmin, for example, has found its niche in the smart watch market, but Apple could always develop a watch that matches Garmin's advantages, but Garmin could never develop a watch that works as well with iOS as the Apple Watch because Apple reserves that functionality for itself. The same is true, and probably even more so, for earbuds.
The platform providers consistently have the advantage of being able, at least in theory, to match the competition for features and then give themselves a leg up by adding additional stuff that only works for their own products.
I'm not going to pretend that there is a clear and easy mitigation. The EU's focus on core features and APIs is an attempt, whether it will work we shall see.