Yesterday evening, Apple released the first preview of macOS Monterey 12.1 to registered developers. In addition to bug fixes, the version also includes SharePlay.
SharePlay allows users to share media within a FaceTime call, including TV shows, movies, and music from multiple providers. Apple Music support is also included, complete with synchronization of playback across multiple users. A screen sharing option is also available. While the feature was introduced with iOS 15.1 and iPadOS 15.1 for iPhone and iPad users, it remains disabled on macOS Monterey 12.0.1.
Monterey: SharePlay for macOS is coming
Now, however, Apple has reactivated the whole thing in the latest macOS Monterey 12.1 beta. Accordingly, the function will probably also be made available for Mac devices with the next macOS update.

The feature was originally supposed to be introduced with iOS 15. But Apple had to postpone the release. In yesterday's announcement explained Apple says developers can create SharePlay experiences for all platforms without relying on the SharePlay developer profile by using the GroupActivities permission. For more information, see the SharePlay for Developers website. (Image: Apple)