I think they’re reworking the Chromecast sharing as it was never working great. An alternative is to use the phone to share the screen and put that on the TV if I remember correctly (or use a laptop or just the phone).
There’s also a few asymmetrical games, where one player plays in VR and the other one flat (there’s probably more):
Regarding isolation: that’s definitely true. But I’d argue most players (flat or VR) play games alone in a room anyways and VR multiplayer games have a bigger social component. But playing with friends and family is definitely more fun.