Hi.  Sonos makes multiroom audio systems.  These systems are their only product.  They own several key patents for such systems, in particular for synching the music perfectly.  There are certainly people who would like to mix Sonos and other brands in their systems, but I suspect that Sonos sees that as commercial suicide.  The balance of the arguments may change, but fir the moment I wouldn’t hold your breath.

And, beyond the technical issues that may apply, there are likely legal reasons that this isn’t done, especially as Sonos wants to ‘play nice’, as much as possible, with the widest possible variety of systems. 

Much the same as their stance on adding content streaming. Sonos doesn’t just grab any content possible, it requires the content owners to ‘authorize’ distribution in the Sonos ecosystem.

In my situation, you could say the same thing about Tesla and either Apple CarPlay, or Android Auto. There’s the customers who want that feature, but Tesla does not allow it.