How to give conditional formatting for a pivot value cell by comparing with other value cells

<Grid.Resources>
<local:BackgroundConverter x:Key="backConverter" />
<Style x:Key="valueCellStyle" TargetType="{x:Type syncfusion:PivotGridTemplateCell}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type syncfusion:PivotGridTemplateCell}">
<StackPanel Background="{Binding Converter={StaticResource backConverter}, ElementName=pivotGrid1}">
<TextBlock Grid.Column="1"
Text="{Binding Path=Text, RelativeSource={RelativeSource TemplatedParent}}" 
TextWrapping="Wrap" HorizontalAlignment="Center"
VerticalAlignment="Center" FontFamily="Segoe UI" FontSize="12"/>
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Grid.Resources>
 

class BackgroundConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if (value is PivotGridControl)
            {
                PivotGridControl pivotGrid = value as PivotGridControl;
                if (MainWindow.CurrentCellRowIndex == 0 && MainWindow.CurrentCellColumnIndex == 0)
                {
                    MainWindow.CurrentCellRowIndex = pivotGrid.PivotColumns.Count +
                    ((pivotGrid.PivotCalculations.Count > 1) ? 1 : 0);
                    MainWindow.CurrentCellColumnIndex = pivotGrid.PivotRows.Count;
                }
                var rawItems = pivotGrid.EditManager.GetRawItemsFor(MainWindow.CurrentCellRowIndex,
                MainWindow.CurrentCellColumnIndex);
                if (rawItems.Count > 0)
                {
                    if (rawItems.Any(i => i is ProductSales && (i as ProductSales).Product == "Bike"))
                    {
                        ////Show yellow color on background if any one record has product property as "Bike"
                        return Brushes.Yellow;
                    }
                    return Brushes.LightBlue; //// else light blue color.
                }
            }
            return null;
        }
        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }