iTunes 12.7.3, according to Apple's release notes, introduces support for the HomePod. A new AirPlay menu built into iTunes 12.7.3 is designed to make it easy to choose the HomePod as an audio source and control what plays next using an Apple Music subscription.
Apple's full release notes for iTunes 12.7.3 are below:
iTunes is now designed to work with HomePod. Use the improved AirPlay menu to easily choose HomePod can control what plays next with your Apple Music subscription. To learn more about HomePod, visit https://www.apple.com/homepod.Today's iTunes update can be downloaded from the Mac App Store for free using the Software Update function.
iTunes 12.7.3 follows iTunes 12.7.2, a December update that also focused on minor improvements. iTunes 12.7, released in September, was the last major update to iTunes, eliminating the built-in App Store to focus solely on music, movies, TV shows, podcasts, and audiobooks.