Last week, Microsoft released Windows 10 SDK Preview build 18890 which was the first SDK build from the 20H1 development branch. Now, they have released another update (build: 18894) that comes with no big changes.
As a Windows Insider, you can download the latest Windows 10 SDK preview from the insider portal or from the direct link shared here.
Apart from a small addition to some APIs and bug fixes, Windows 10 SDK Preview build 18894 doesn't include any big changes on top of the previous build.
Like all other previous SDK preview builds, you can use this SDK build in a production environment along with the previously released SDKs. Make sure that you are running Windows 10 Insider Preview build to install the SDK. You will also need Visual Studio 2017 or higher to build apps, which can be downloaded from the below links:
Point to note that, if your apps are targeting Windows 10 build 1903 or earlier, then ONLY you can continue to submit your apps to the Microsoft Store by installing this SDK. Side-by-side, you can start preparing your apps for the Windows 10 feature update (20H1) that's going to release in early 2020.
If you'd like to download the latest the Windows 10 SDK Preview build 18894, you can get it from here. In order to assist with script access to the SDK, the direct link of the ISO image is also available for offline installation.