Apple has introduced incremental updates for iOS, iPadOS, watchOS, tvOS and HomePod. All have received x.1 updates, which introduce several new features including SharePlay.
https://www.notebookcheck.net/Apple-releases-iOS-15-1-iPadOS-15-1-watchOS-8-1-tvOS-15-1-and-HomePod-15-1.575697.0.html