I'm skeptical on the widespread adoption of ZB's "metaverse" on the grounds that most people simply prefer spending time in reality as opposed to wearing a headset and getting lost in a 3d world, and it isn't a matter of tech/hardware but rather human nature.
But I watched the top video on your twitter page and I appreciate your enthusiasm and down-to-earth explanation of how you see value in the idea.
The TAM with just gaming is huge and that use case alone makes sense to me, but does rely on interoperability to be useful from the consumer perspective as you discussed.
I don't see any incentive whatsoever for existing big tech companies like FB to build an interoperable metaverse unless they retain significant/dominant control over it. In Facebook's case, their entire business is premised on being a walled garden, but they love when people build games and apps within that garden!
In any case I'll have to think about the notion of portals and portable avatars further & will follow your progress!