Windows 10 20H1 Build 18841 is out for Insiders part of the Skip Ahead and it comes with normal bug fixes as Microsoft isn’t ready to test new features yet. Microsoft plans to begin releasing 19H2 bits to Insiders later this spring after the 19H1 is nearly finished and ready for the general public. Windows Sandbox now supports configuration files allowing users to configure some aspects of the sandbox, such as vGPU, networking and shared folders. Microsoft will use the Release Preview ring for previews of drivers and quality updates.
Source: https://www.bleepingcomputer.com/news/microsoft/windows-10-20h1-build-18841-released-to-skip-ahead-insiders/