Other app stores that are approved by Apple while giving Apple a cut after a million downloads of an app.

You still can’t install whatever .ipa file you want on iOS, even in Europe.

What really needs to happen is that the consumer needs to own the device they bought. What this means in the smartphone world is a few things: root access, unlockable bootloader, and replacable signing keys for the primary bootloader while providing a firmware package to go back to 100% stock (so no Samsung Knox that irrevocably triggers after unlocking the bootloader, or DRM keys that get irrevocably wiped when unlocking the bootloader) (all of these being optional features that the user has to explicitly enable). Anything short of that is not ownership.