Never heard of it, but that’s not a metric that you should value. :)

Sonos can’t just “add” streams willy nilly. Those streams have to request to be added to the Sonos ecosystem, as detailed in the Sonos partners page.

My guess is there are legal issues around that. 

So, you should send the folks at this PodCastOne company, and point them at that link, and ask them if they’d like to be a part of the Sonos family.