For when you need refout rather than refonly two produce two artifacts: a ref assembly NuGet package, and a non-NuGet distribution mechanism for the lib assembly.

Ref assembly NuGet package with refout.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <!-- ... -->

  <!-- Ref assembly NuGet packaging -->
  <PropertyGroup>
    <ProduceReferenceAssembly>true</ProduceReferenceAssembly>
    <BuildOutputTargetFolder>ref</BuildOutputTargetFolder>
    <TargetsForTfmSpecificBuildOutput>$(TargetsForTfmSpecificBuildOutput);UseRefAssemblyAsBuildOutputInPackage</TargetsForTfmSpecificBuildOutput>
  </PropertyGroup>
  <Target Name="UseRefAssemblyAsBuildOutputInPackage">
    <ItemGroup>
      <BuiltProjectOutputGroupOutput Remove="@(BuiltProjectOutputGroupOutput)" />
      <BuildOutputInPackage Include="@(IntermediateRefAssembly)" />
    </ItemGroup>
  </Target>

</Project>