DataGrid: BGrouping

is it possible to trigger grouping based on grouping count; also it it possible to style the grouping such as background etc? An example would be appreciated. Thank you.

No, this is not supported.

You can check this demo: Free Blazor Components | 60+ controls by Radzen the group heading template allows you to customize the appearance:

<GroupHeaderTemplate>
   @context.GroupDescriptor.GetTitle(): @(context.Data.Key ?? ""), Group items count: @context.Data.Count, Last order date: @(context.Data.Items.Cast<Order>().OrderByDescending(o => o.OrderDate).FirstOrDefault()?.OrderDate)
</GroupHeaderTemplate>