We believe the latest .NET 9 preview versions of Microsoft.NET.ILLink may contain a packaging error. This nuget now declares a package dependency on ILCompiler.DependencyAnalysisFramework, which doesn't appear to be available:

D:\a_work\1\s\src\Microsoft.Android.Sdk.ILLink\Microsoft.Android.Sdk.ILLink.csproj : error NU1101: Unable to find package ILCompiler.DependencyAnalysisFramework. No packages exist with this id in source(s): darc-pub-dotnet-emsdk-fcd8602, darc-pub-dotnet-runtime-0ece505, dotnet-eng, dotnet-public, dotnet-tools, dotnet8, dotnet8-transport, dotnet9, dotnet9-transport, xamarin.android util