Well, not directly, for most people that would be via Apple/Google stores. And of course these stores could have secret functionality for shipping targeted upd

Well, not directly, for most people that would be via Apple/Google stores. And of course these stores could have secret functionality for shipping targeted updates. But if it exists, this means that 1) none of the developers working on the store backend decided to leak info about it and 2) none of the targets have had an expert look at their device to find an unusual update that wasn't seen by anyone else. Over time, the probability of either of those things happening would be going up…