The SDK link doesn't work anymore though, results in "403 Forbidden"
Here is a new one:
Get SDK Insider Preview – Build 22557
Notes:
Installation on an operating system that is not a Windows Insider Preview build is not supported and may fail.
Support in .NET for targeting the Windows Insider SDK and TFM is available in .NET 6 and .NET 5 (with 5.0.8 or later). To access new APIs in the Windows Insider SDK, .NET developers can set the following properties in their project file:
For targeting .NET 6:
<PropertyGroup>
<TargetFramework>net6.0-windows10.0.22557.0</TargetFramework>
<UseWindowsSdkPreview>true</UseWindowsSdkPreview>
</PropertyGroup>
For targeting .NET 5:
<PropertyGroup>
<TargetFramework>net5.0-windows10.0.22557.0</TargetFramework>
<UseWindowsSdkPreview>true</UseWindowsSdkPreview>
</PropertyGroup>
These properties allow .NET 5+ developers to opt-in to using preview packages for the Windows Insider SDK.