I don't care if the data is locked down or not, the social graph isn't the interesting part of a "metaverse" and in some ways it is probably better locked up and that can remain Facebook's lock in to keep them interested in the project. The kind of garden walls I was talking about are more federative: bringing external content in, but in ways that are true to the outside content; not just confined to Facebook looks and styles and components, not confined to a bare amount of customization of boring card styles, not embedded in a "Facebook way" but in a "web way" (whatever that means, and it doesn't really feel like it means much at all after the imagination and wilds of the 1990s).
I referenced the anarchy and chaos of blogs and MySpace, specifically: it's about user control to "do ugly things", to escape the gray walls and graffiti "their spaces". If Facebook is a "space" today, it's a building full of cubicles all alike. Sure, you can hang photos in the cubicles and they've got colorful stock ones, but your still constrained to just those cubicle walls and they mandate a lot about the allowed size and frame styles. That's almost directly the antithesis of a user owned "metaverse" whether 2D or 3D.
They used to be open. Cambridge Analytica came along and congress made them decide open was a liability. Sure they were starting to close down before congress, but now they're sure as hell not opening up.