Meta Horizon Worlds launched in 2021, so I guess it doesn't count. (Meta continues to invest in it.)

VIVERSE (from HTC) was announced in March 2022. It's still around. It's something you can do with your HTC VIVE headset. It's kinda like HTC's competitor to Meta Horizon Worlds. HTC continues to invest in it. For example, in August of 2024, they announced "VIVERSE Create v1.0" a no-code tool to create interactive multiplayer worlds (for VIVERSE).

I think the vast majority of them were early stage prototypes either done by companies "labs" with no attention span or students.

Either way I don't think it cost people a lot to move on, most likely to AI projects

VR Chat was already the only "metaverse" anyone cared about, and Meta couldn't make it a "thing" so the world moved on.

Waiting on devices to have mass market appeal. The metaverse will materialize with smart glasses