A new Windows 10X Emulator image with Build 10.0.19578.0 is now available to download and use for developers. You can go and download the new Windows 10X emulator image by clicking on the download box below.
As per the description provided in the store listing.
This is an optional package for use with the Microsoft® Emulator. This package provides a guest image for Windows 10X devices, version 10.0.19578.0.
The last emulator image build was 10.0.19563.0 and it resulted in leak of many new details about Windows 10X. Enthusiasts also ported it to many non dual-screen devices.