Mozilla has long been interested in adding AR/VR capabilities to the browser

https://developer.mozilla.org/en-US/docs/Web/API/WebXR_Devic...

At a certain point you might not have enough third party devs to really exercise an API or drive adoption and developing a first party app is a good way to get the party started.

Assuming all the action takes place in a confined room it is not a particularly difficult problem to solve compared to an OASIS or Sword Art Online-like virtual environment which would have the problems of an open world game to solve.

It makes it look like Mozilla is doing something while not actually doing anything meaningful.

Needing new revenue sources, even if they appear to be a gamble unlikely to hit.

I would guess from Mozilla's point of view: "Not leaving the Metaverse up to Meta"

I think you'd need way more resources to bet Meta

Fun?