Instead of allocation on inventory, it's possible to allocate on supply orders which are created automatically upon creating a new order item. It's called direct allocation.
As an example the order in the image below has 2 items. The chair has a normal product allocation which will create a reservation in Clougistic. The prepacked item will be allocated direct.
chair:
a reservation will be created, to get this item allocated we need free inventory (purchase or produce this item)
prepacked:
no reservation will be created.
a supply order will be created (production/purchase) automatically upon processing of the order.
chair:
as there is a reservation the normal allocation rules apply (FIFO)
prepacked:
this particular item will be received for the order item in order 38748. It means that the inventory location will be assigned to the order item.
chair:
system will follow the zone sorting method.
prepacked:
picker will be forced to pick from the inventory location assigned during the receiving step.
To be able to process the supply order automatically it's import to have a supplier and supplier product for the prepacked item.