Microsoft released a new Windows 10 Insider Preview Build 18309 from the 19H1 branch to the Windows Insiders in the fast ring. Though this build does not include long features list, but includes a notable changes to the Windows experience.
If you are a Windows Insider in the Fast ring, check for updates. But before that, check the known issues that still present in this new preview build.
Along with Windows 10 Insider Preview Build 18305, which was released end of last year, Microsoft announced new sign-in experience with password-less phone number account and streamlined Windows Hello PIN reset experience to Windows 10 but that was limited to Windows 10 Home edition at that time.
With this new build (Windows 10 Insider Preview Build 18309), these features are not rolling out to all Windows 10 editions. You can now set up and sign-in to Windows 10 with a phone number account, without having to create, or deal with the hassle of a password. You can also reset the Windows Hello PIN directly from the sign-in screen.
Apart from these features, Microsoft also improved the Narrator and Ease of Access to have a great experience. This build also includes a lot of general changes, improvements and bug fixes; and also includes a list of known issues. Don't forget to checkout the original Release Notes published by Microsoft.