The new macOS Mojave 10.14.4 beta can be downloaded through the Software Update mechanism in System Preferences after the proper profile has been installed from Apple's Developer Center.
macOS Mojave 10.14.4 brings Apple News to Canada for the first time, allowing Canadian Mac users to access news stories in French, English, or both.
The update also includes support for Safari AutoFill using Touch ID and automatic dark mode themes in Safari. That means if you have Dark Mode enabled, when you visit a website that has an option for a dark theme, it will be activated automatically. You can see a demo of the feature here.
We're expecting Apple to release macOS Mojave 10.14.4 alongside iOS 12.2, tvOS 12.2, and watchOS 5.2 following the company's services-focused March 25 event.