How to load a file from the installation folder of a C++ WinUI 3.0 application

I'm porting a UWP app over to Win32 with WinUI 3.0. In that UWP app I'm loading file resources from the app installation folder as follows:

std::vector<char> MyStorage::ReadFileFromStorageFolder(const std::wstring& relativePath)
{
  path filePath = path{ Package::Current().InstalledLocation().Path().data() } / path{ relativePath };

  std::ifstream           inputFileStream(filePath, std::ios::binary | std::ios::ate);
  std::ifstream::pos_type pos = inputFileStream.tellg();

  std::vector<char> result(pos);

  inputFileStream.seekg(0, std::ios::beg);
  inputFileStream.read(&result[0], pos);

  return result;
}

Unfortunately, the code Package::Current().InstalledLocation() causes the Win32 WinUI 3.0 app to hang. How would I do this so that it works in the Win32 WinUI 3.0 app?