The general idea of "the metaverse" at least as it exists in sci-fi is that there's only one - it's the metaverse, a singular, canonical, ubiquitous layer of VR over the real world. The assumption here is that, because Facebook is doing it, it will eat the world through sheer force of will. Every other platform will either be assimilated by Meta or rendered obsolete by Meta's control over standards and influence over governments. Facebook wins without even stepping into the ring, the game's already over, omae wa mou shindeiru.

I personally don't think it will go that way - I think no matter what Facebook does, it's just going to wind up as one of many attempts at VR in the marketplace (it's too late to capture the market and own it now IMO, and i just don't trust VR to ever be more than niche, even in gaming) which means the "metaverse" in this case is just marketing and hype.