Microsoft have released the first Windows 10 20H1 build to the slow ring. The build is 19013.1122 which was released to the fast ring a couple of week’s ago. With the November 2019 Update complete Microsoft have moved 20H1 to the slow ring.
I have found the 20H1 development has been very stable and no issues with recent builds. I don’t think it will be long until we get the fast ring changed over to the next development of Windows 10.
Here is my video looking at 19013