I might be terribly outdated but I don't think the order tables have been converted to views. What were "converted" was catalog tables in Commerce 9

Get Sorted list of PurchaseOrder for logged-in customers (mostly used for order history)

var purchaseOrders = OrderContext.Current.LoadByCustomerId<PurchaseOrder>(PrincipalInfo.CurrentPrincipal.GetContactId())
                                             .OrderByDescending(x => x.Created)
                                             .ToList();

Get the list of orders using Order search (normally used if you need to create a report or export orders to external integration point)

public IEnumerable<PurchaseOrder> GetEpiOrders(int maxOrders)
        {
            var parameters = new OrderSearchParameters
            {
                SqlWhereClause = "Your-Criteria-to get-qualified-orders"
            };
            var classes = new StringCollection { OrderContext.Current.PurchaseOrderMetaClass.Name };

            var searchOptions = new OrderSearchOptions { Classes = classes, RecordsToRetrieve = maxOrders };
            var orders = OrderContext.Current.Search<PurchaseOrder>(parameters, searchOptions);

            return orders;
        }

I hope that helps

In the Episerver Commerce 13.x the Order By clause only works for 'OrderGroupId', we can not pass any meta field name to sort the records.

e.g. orderSearchParameters.OrderByClause = "OrderGroupId DESC";

This would probably be a feature request for a future release.