Guess it's not available for sale to customers yet because it doesn't fit in any segment. However, it is available for renting but only in San Francisco from what I've gathered:
"The Nissan New Mobility Concept is currently not available for customers to purchase in America as the vehicle is yet to be categorised into a particular segment."
I can see it being sold to customers down the road though as it's already being sold in other parts of the world like Europe...