My understanding of it so far is that it is at most, 50 or 100 houses as a test... It's a startup that wants to make it wide scale but hasn't got there yet.
https://www.google.com/search?client=firefox-b-d&q=span+resi...
https://www.google.com/search?client=firefox-b-d&q=span+resi...
https://www.span.io/blog/span-announces-xfra-a-distributed-d...