MainPage.xaml

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:dx="http://schemas.devexpress.com/maui"
             xmlns:local="clr-namespace:CustomAppearance"
             xmlns:ios="clr-namespace:Microsoft.Maui.Controls.PlatformConfiguration.iOSSpecific;assembly=Microsoft.Maui.Controls"
             ios:Page.UseSafeArea="false"
             x:Class="CustomAppearance.MainPage">
    <ContentPage.BindingContext>
        <local:TestOrderRepository/>
    </ContentPage.BindingContext>
    <dx:DataGridView x:Name="grid" ItemsSource="{Binding Orders}"
                      RowHeight="40" TotalSummaryHeight="40">
        <dx:DataGridView.Columns>
            <dx:TextColumn FieldName="Product.Name" Caption="Product" Width="150" />
            <dx:NumberColumn FieldName="Product.UnitPrice" Caption="Price" 
                          DisplayFormat="C0" MinWidth="100"/>
            <dx:NumberColumn FieldName="Quantity" MinWidth="100"/>
            <dx:NumberColumn FieldName="Total" 
                          UnboundType="Integer" UnboundExpression="[Quantity] * [Product.UnitPrice]" 
                          IsReadOnly="True" DisplayFormat="C0" MinWidth="100"/>
            <dx:DateColumn FieldName="Date" DisplayFormat="d" MinWidth="100"/>
        </dx:DataGridView.Columns>
        <dx:DataGridView.TotalSummaries>
            <dx:GridColumnSummary FieldName="Total" Type="Sum"/>
        </dx:DataGridView.TotalSummaries>

        <!--Customize the appearance of grid cells.-->
        <dx:DataGridView.CellAppearance>
            <dx:CellAppearance Padding="5" BackgroundColor="#333333" BorderColor="#515151"
                       FontSize="14" FontColor="White" 
                       SelectionColor="#f78a09" SelectionFontColor="Black"/>
        </dx:DataGridView.CellAppearance>

        <!--Customize the appearance of column headers.-->
        <dx:DataGridView.ColumnHeaderAppearance>
            <dx:ColumnHeaderAppearance BackgroundColor="#333333" BorderColor="#515151" 
                               FontSize="16" FontColor="#929292" FontAttributes="Bold" 
                               HorizontalLineThickness="2"/>
        </dx:DataGridView.ColumnHeaderAppearance>

        <!--Customize the appearance of the total summary panel.-->
        <dx:DataGridView.TotalSummaryAppearance>
            <dx:TotalSummaryAppearance Padding="2, 10" BackgroundColor="#666666" BorderColor="#515151"
                               FontSize="14" FontColor="#f78a09"/>
        </dx:DataGridView.TotalSummaryAppearance>
    </dx:DataGridView>
</ContentPage>