How to use non-inventory items on a discrete work order

Summary:

My customer would like to create sales orders for service items. The items are non-inventory items, because they are services.

After submitting the sales order, the sales order is submitted into the order orchestration flow. It has the status waiting for billing.

My customer would like to have a work order created instead of immediately billed.

My customer would like to be able enter how many hours are used to for this work order / sales order.

Can we use finished good items on a discrete manufacturing work order which are non-inventory tracked and not purchasable?

We are not using the maintenance module, only the discrete manufacturing module.