The launch comes after DuckDuckGo Privacy Essentials had to be removed from the Safari extensions gallery following major changes introduced in Safari 12 that made the extension incompatible. From the DuckDuckGo website:
As you may be aware, major structural changes in Safari 12 meant that we had to remove DuckDuckGo Privacy Essentials from the Safari extensions gallery. With Safari 13, new functionality was thankfully added that enabled us to put it back. Consequently, you'll need Safari 13+ on macOS 10.15 (Catalina) or newer to install the updated version.
DuckDuckGo Privacy Essentials blocks hidden third-party trackers on websites and features a Privacy Dashboard, which generates a Privacy Grade rating (A-F) information card whenever a user visits a site. The rating aims to let them see at a glance how protected they are, while providing additional options to dig deeper into the details of blocked tracking attempts.
While the extension doesn't include private search, DuckDuckGo Search is built into Safari as a default search option, and they work together to help users search and browse privately.