Is there a better way to include additional PDB files in a symbol package during dotnet pack?

[mu88]

I'm currently using a custom MSBuild target (AddHealthCheckSymbolsToSymbolPackage) to manually unzip the .snupkg file, add an extra PDB (from a referenced project), and re-zip the symbol package. This is needed because my NuGet package includes both mu88.Shared.dll and mu88.HealthCheck.dll, but only mu88.Shared.pdb is included by default in the symbol package.

Excerpt from my mu88.Shared.csproj:

<!-- To support proper Source Link debugging, we need to include the PDB files of all assemblies in the symbol package. -->
<!-- Since the NuGet package contains both mu88.Shared.dll and mu88.HealthCheck.dll, mu88.HealthCheck.pdb has to be added to the symbol package, too. -->
<!-- Unfortunately, I haven't found (yet) a better way of embedding the additional debug symbol file than manually manipulating the the package with custom MSBuild logic. -->
<Target Name="AddHealthCheckSymbolsToSymbolPackage" AfterTargets="Pack">
  <PropertyGroup>
    <TemporarySymbolPackageModificationDirectory>$(PackageOutputPath)temp</TemporarySymbolPackageModificationDirectory>
  </PropertyGroup>

  <ItemGroup>
    <AdditionalDebugSymbols Include="$(OutputPath)/mu88.HealthCheck.pdb"/>
  </ItemGroup>

  <Message Text="Unzipping symbol package to '$(TemporarySymbolPackageModificationDirectory)'..." Importance="high" />
  <Unzip
    SourceFiles="$(PackageOutputPath)/$(PackageId).$(Version).snupkg"
    DestinationFolder="$(TemporarySymbolPackageModificationDirectory)"
    OverwriteReadOnlyFiles="true"
  />

  <Message Text="Deleting existing symbol package '$(PackageOutputPath)$(PackageId).$(Version).snupkg'..." Importance="high" />
  <Delete Files="$(PackageOutputPath)$(PackageId).$(Version).snupkg" />

  <Message Text="Adding additional debug symbols to '$(TemporarySymbolPackageModificationDirectory)/lib/$(TargetFramework)'..." Importance="high" />
  <Copy
    SourceFiles="@(AdditionalDebugSymbols)"
    DestinationFolder="$(TemporarySymbolPackageModificationDirectory)/lib/$(TargetFramework)"
  />

  <Message Text="Repacking symbol package from '$(TemporarySymbolPackageModificationDirectory)' to '$(PackageOutputPath)$(PackageId).$(Version).snupkg'..." Importance="high" />
  <ZipDirectory
    SourceDirectory="$(TemporarySymbolPackageModificationDirectory)"
    DestinationFile="$(PackageOutputPath)$(PackageId).$(Version).snupkg"
    Overwrite="true" />

  <Message Text="Cleaning up temporary directory '$(TemporarySymbolPackageModificationDirectory)'..." Importance="high" />
  <RemoveDir Directories="$(TemporarySymbolPackageModificationDirectory)" />
</Target>

Is there a more idiomatic or supported way to include additional debug symbol files (PDBs) from referenced projects in the symbol package when running dotnet pack?
Ideally, I'd like to hook into an existing MSBuild target or use a built-in mechanism, rather than manipulating the package manually, e.g. something similar to <IncludeAssets>mu88.HealthChecker.dll</IncludeAssets> (taken from here).

Any advice or pointers to documentation would be appreciated! Thanks!