Google is building its own DeX: First look at Android's Desktop Mode

Of course they will enshitten it into unusability, but in theory they could put one over on Apple with this. It's "only" the software that stops Apple's iDevices from being usable as development platforms or general purpose computers. Google could offer something here that Apple won't.

OTOH this seems like exactly the sort of thing that Apple could suddenly announce at a september event. As you say, there are no hard technical barriers to getting this working.

Apple may come up with new surprises but I would be very surprised if this came to pass.