This is what I’m reading...
Today, almost four months after the HomePod’s release, HomePod users can access the new features through
a software update available through the Home app in iOS 11.4, which includes AirPlay 2, Apple’s wireless audio technology that enables HomePod pairing. HomePods can now sync with other HomePods or third-party, AirPlay-2-enabled speakers, and play music throughout your home. Bose, Sonos, Beats, Bowers & Wilkins, and Libratone are
some of the companies that have announced AirPlay 2 compatibility for current and upcoming speakers.