At I understand, this specifically affects Apple because there is no possible alternative marketplace on iOS. As much as Google sets up roadblocks to installing

At I understand, this specifically affects Apple because there is no possible alternative marketplace on iOS. As much as Google sets up roadblocks to installing apps outside of Google Play, it's still straightforwardly possible to install FDroid or the Epic Store or whatever you want. I don't know much about Amazon's Android fork, but I assume it's possible to sideload an appstore there too (though I could be wrong).