https://github.com/NuGet/Home/issues/5986#issuecomment-732401471
I've found that you can manually control which .dlls to reference and which .dlls to copy to output from a NuGet package if you turn off all assets on the PackageReference:
<PackageReference Include="Foo.MyPackage" Version="1.0.0" ExcludeAssets="all" GeneratePathProperty="true" />
and then manually reference the .dlls you need:
<Reference Include="$(PkgFoo_MyPackage)\lib\net45\CopyThis.dll">