FB's Metaverse is really a hardware push, they want to control hardware. FB misses the smart phone boat, which is now controlled by Google and Apple. Once you control the hardware and its ecosystem, you can control Metaverse world. Apple banned FB's privacy tracking, that created massive headache on FB. Mark doesn't want to be in that position, ever again.
Think of Metaverse as fully immersive social media, gaming, etc.. It's place where people can do stuff with minimum interference from others. Wanna watch a NBA game? Put on the head set and you'll be court side.