Export with aggregating relationship (sum)

TextColumn::make('items_sum_actual_weight_value')
    ->sum('items', 'actual_weight_value')
    ->label('Total Weight')

ExportColumn::make('items_sum_actual_weight_value')
    ->sum('items', 'actual_weight_value')
    ->label('Total Weight'),

public static function modifyQuery(Builder $query): Builder
{
    return $query
        ->withSum('items', 'actual_weight_value')
        ->withCount('items');
}