public Table GetTable()

{
  await QueuedTask.Run(() =>
  {
    IEnumerable<Layer> layers =
      MapView.Active.Map.Layers.Where(layer => layer is FeatureLayer);

    foreach (FeatureLayer featureLayer in layers)
    {
      using (Table table = featureLayer.GetTable())
      using (Datastore datastore = table.GetDatastore())
      {
        if (datastore is UnknownDatastore)
          continue;

        Geodatabase geodatabase = datastore as Geodatabase;
      }
    }
  });
}

{
  //Must be called within QueuedTask.Run()
  void GetCount(FeatureLayer featureLayer)
  {
    // Row count in a Table
    Table table = featureLayer.GetTable();
    long count = table.GetCount();

    // Feature count in a FeatureClass
    FeatureLayer lyr = MapView.Active.Map.GetLayersAsFlattenedList().OfType<FeatureLayer>().FirstOrDefault();
    FeatureClass featureClass = lyr.GetFeatureClass();
    count = featureClass.GetCount();
  }
}

{

  // Note: QueuedTask is required to access the AnnotationFeature
  {
    using var table = annotationLayer.GetTable();
    using var rc = table.Search();
    rc.MoveNext();
    using var af = rc.Current as AnnotationFeature;
    var graphic = af.GetGraphic();
    var textGraphic = graphic as CIMTextGraphic;

    //Note: 
    //var outline_geom = af.GetGraphicOutline(); 
    //gets the anno text outline geometry...
  }
}