public static Task<IMapPane> CreateMapPaneAsync( 
   PaneCollection paneCollection,
   CIMMapView mapView
)

{
    //Finding the first project item with name matches with mapName
    MapProjectItem? mpi = Project.Current.GetItems<MapProjectItem>()
      .FirstOrDefault(m => m.Name.Equals("The Map", StringComparison.CurrentCultureIgnoreCase));
    //Note: Needs QueuedTask to run
    var mapFromItem = mpi?.GetMap();
    if (mapFromItem != null)
    {
        //Open the map in a new map pane
        //Must be called from the UI thread
        await ProApp.Panes.CreateMapPaneAsync(map);
    }
}

{
    //Assume we get the selected webmap from the Project pane's Portal tab
    if (Project.Current.SelectedItems.Count > 0)
    {
        if (MapFactory.Instance.CanCreateMapFrom(Project.Current.SelectedItems[0]))
        {
            map = MapFactory.Instance.CreateMapFromItem(Project.Current.SelectedItems[0]);
            await ProApp.Panes.CreateMapPaneAsync(map);
        }
    }
}