Just after iOS 10.3 beta 4 (read: iOS 10.3 beta 4 available for developers and testers), Apple released Monday evening the fourth beta of its macOS 10.12.4 operating systems for MacOS compatible with macOS Sierra and watchOS 3.2 for Apple Watch 1 and Series 2. Yesterday is the firmware tvOS 10.2 beta 4 for the fourth generation Apple TV (2015) which has been made available to developers.
If you have an account in the Apple Dev Center and you installed the previous pre-version of macOS 10.12.4 on your apple computer, you can download and install beta 4 of macOS 10.12.4 from tab Updates from the Mac App Store. It has the build number 16E175b against 16E163f for the 3rd.
For developers with an Apple Watch, launch the eponymous application on your iPhone and go to the settings to upgrade to watchOS 3.2 beta 4. For Apple TV 4, the 4th pre-release of tvOS 10.2 can be easily recovered from the settings of the box.