I don't think you could compete with the exact same product... the advantage of scale would still give Apple more than sufficient edge.
However if you happened to like E.G. Apple's screen, or camera, or another component that was better than what else could be selected it could be part of a design which competed on other merits. E.G. maybe the touch digitizer is just that much better, so it might make sense on some models of Android or some Libre phone more closely based on Linux or BSD. Or some company that makes an iPhone like device but to GOV spec standards for a given country. (In my mind, I'm thinking US Gov, but IP laws tend to be International too, so maybe Germany wants it's own secure phone.)
However if you happened to like E.G. Apple's screen, or camera, or another component that was better than what else could be selected it could be part of a design which competed on other merits. E.G. maybe the touch digitizer is just that much better, so it might make sense on some models of Android or some Libre phone more closely based on Linux or BSD. Or some company that makes an iPhone like device but to GOV spec standards for a given country. (In my mind, I'm thinking US Gov, but IP laws tend to be International too, so maybe Germany wants it's own secure phone.)