Some files are taken from VSSDK tools

[nohwnd]

      <VsixSourceItem Include="$(VSSDKBuildToolsFolder)System.Diagnostics.DiagnosticSource.dll" />
      <VsixSourceItem Include="$(VSSDKBuildToolsFolder)System.Runtime.CompilerServices.Unsafe.dll" />

are taken from vssdk package, this does not look like the correct place to take them from, there are dedicated public packages available, use them instead of the sdk package that should be there only to be able to produce a vsix package