I am curious why Sonos does not provide a device to integrate a 3rd party sub as a subwoofer only. That would provide significant options for end users.
It is true that Sonos can integrate a 3rd party sub as part of integrating 3rd party mains, but that will not integrate with a Sonos sound bar, only a Sonos Sub can.
Ideally, a device to do this would only provide a preamp output for the sub, but it could be as simple as a configuration option for an AMP where only the sub is used. Users could then add their sub to a Sonos soundbar without grouping in mains as well, with the potential problems that arise from that. Could be as simple as a software update. How about it, Sonos?