SmartAssembly MSBuild task can be used to protect assemblies inside a NuGet package.

1. Open your .NET Standard project in Visual Studio.
2. Build it in Release mode.
3. Add reference to RedGate.SmartAssembly.MSBuild NuGet package.
4. Open SmartAssembly and:
   • Choose assembly from Release folder as main assembly.
   • Choose any location for destination assembly.
   • Save the project next to .csproj with the same name.

5. Edit your .csproj and add a new property:

   <PropertyGroup>
     ...	
     <SmartAssemblyOverwriteAssembly>true</SmartAssemblyOverwriteAssembly>
   </PropertyGroup>

6. Use dotnet pack -c Release command-line command to create a NuGet package from your .NET Standard project (or use Publish/Pack option in Visual Studio).
7. The created .nupkg file will contain an obfuscated version of your assembly.