[eighthave]

I agree with basically all the points in this thread, one thing that is missing is that most of these points are not mutually exclusive. A decentralized system like F-Droid does not close out the possibility of walled gardens, it just gives users choice of whether they want to remain in it. For example, you can buy a CalyxOS device now and only enable F-Droid as the app source. That is a walled garden of the safest kind: all free software reviewed by bots and humans before inclusion. Users then can opt into other sources.

We have recently implemented some rudimentary controls where you can use Device Admin mode to lock F-Droid to a given set of repositories. That strictly enforces the walled garden, but doesn't require a single monopolist have all the power.