You can use the IWebBrowser2::Navigate2 Method, something like this:

int main()
{
  CoInitialize(nullptr);
  {
    // build the optional VARIANT 
    // https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-oaut/e93f90dc-8afb-434f-afa9-94f8564fe19b
    VARIANT optional;
    VariantInit(&optional);
    V_VT(&optional) = VT_ERROR;
    V_I4(&optional) = DISP_E_PARAMNOTFOUND;

    IShellWindows* windows;
    if (SUCCEEDED(CoCreateInstance(CLSID_ShellWindows, nullptr, CLSCTX_ALL, IID_PPV_ARGS(&windows))))
    {
      long count;
      windows->get_Count(&count);
      for (auto i = 0; i < count; i++)
      {
        VARIANT index;
        VariantInit(&index);
        V_VT(&index) = VT_I4;
        V_I4(&index) = i;

        IDispatch* obj;
        if (SUCCEEDED(windows->Item(index, &obj)))
        {
          IWebBrowser2* app;
          if (SUCCEEDED(obj->QueryInterface(IID_PPV_ARGS(&app))))
          {
            // get a PIDL from a path
            // note pidl could represent a virtual folder too
            auto pidl = ILCreateFromPath(L"c:\\temp");
            if (pidl)
            {
              // build a VARIANT from the PIDL
              VARIANT url;
              VariantInit(&url);
              if (SUCCEEDED(InitVariantFromBuffer(pidl, ILGetSize(pidl), &url))) // propvarutil.h
              {
                app->Navigate2(&url, &optional, &optional, &optional, &optional);
              }
              VariantClear(&url);
              ILFree(pidl);
            }
            app->Release();
          }
          obj->Release();
        }
        VariantClear(&index);
      }
      windows->Release();
    }
  }
  CoUninitialize();
  return 0;
}