As well as the new iOS 10.3.3 beta Apple also release a new beta of their macOS, the latest one is macOS Sierra 10.12.6 beta 3.
The macOS Sierra 10.12.6 beta 3 has been released to both developers and also Apple’s Public Beta testing program.
As yet there are no details on any major new features in the macOS Sierra 10.12.6 beta 3, the update appears to be mainly bug fixes and performance improvements.
The new macOS Sierra 10.12.6 beta 3 is now available to download fro members of Apple’s Public Beta testing program and also developers.
Source MacRumors