Here are the details from Cheddar's Alex Heath, who cites unnamed sources:
The main feature will be video chat, and Facebook will use facial recognition to tag users and follow them around the room. (Amazon's Echo Show and Google-powered smart displays don't identify users' faces, though some security cameras do.)
The device will have a privacy shutter to disable the camera tracking, but amazingly, Facebook may have only thought to include this in response to its own recent privacy scandals.
While the device was once rumored to rely a homegrown voice assistant to handle basic commands, Portal may instead lean on Amazon's Alexa for things like music, recipes, and news briefings.