public IReadOnlyList<Item> LayerTemplatePackages {get;}

//Gets the collection of layer template packages installed with Pro for use with maps
var items = MapView.Active.Map.LayerTemplatePackages;
//Iterate through the collection of items to add each Map Note to the active map
foreach (var item in items)
{
  //Create a parameter item for the map note
  var layer_params = new LayerCreationParams(item);
  layer_params.IsVisible = false;
  await QueuedTask.Run(() =>
  {
    //Create a feature layer for the map note
    var layer = LayerFactory.Instance.CreateLayer<Layer>(layer_params, MapView.Active.Map);
  });
}