John Gruber writes (emphasis mine):

At the end, he makes the case that each new generation of computing devices has an open alternative and a closed one from Apple. (It’s interesting to think that these rivalries might be best thought of not as closed-vs.-open, but as Apple-vs.-the-rest-of-the-industry.) I’m not quite sure where he’s going with that, though, because I don’t really see how my Quest 3 is any more “open” than my Vision Pro. Are they going to license the OS to other headset makers?

The Quest system software is Android at its core, with Meta’s software running on top. Quest lets you connect to a PC and use it as a VR headset for it, install whatever app you want, whereas Apple locks it down tightly to their ecosystem. Their app marketplace, their rules. I think that’s more so what Zuck was getting at there: Meta simply isn’t keeping things as tight with their platform like Apple is. There are rules and restrictions, of course, even Android itself has them–but they’re not aggressive about it.

As for your question itself, Meta could probably license the OS to other headset makers within the scope of Android’s open-source license, but I doubt they will. There are a lot of potential issues with that and Meta has a lot of proprietary stuff running on top of what is, again, essentially Android.

I think what we’re likely going to see is the walls coming down even further than they already are on Meta’s side. They already have the price advantage with their own product line, so I don’t really see why they wouldn’t want to open things up even further.