I want to know how to cancel a whole FO and OS. There is a core action for cancel a FO item but is there something similar for the Order Summaries or complete Fulfillment Orders?
We have also seen that you can reduce orders (orderitems), but from my understanding you can do this before the fulfillment orders.
The main reason for this is when a package is lost during shipping
Fulfillment Order object have a standard field called Status which also contains Status Category as well. Rather than Status, Status Category decides what will happen to the Fulfillment Order record. By default, the Canceled status is assigned to the Canceled Status Category. Status category means Salesforce performs some actions behind the scene that's why you can't change the status after once Fulfillment Order record is Canceled.
In order to cancel the whole Fulfillment Order record, all you need to do is select the appropriate status (Canceled) and Fulfillment Order will be canceled.
There is no such core action for Order Summary because it doesn't have Status Category which means you can go back and forth with the Order Summary records but you can't do the same with Fulfillment Order records.
Regarding adjustments, you can use after Fulfillment Order creation as well. See Post-fulfillment https://help.salesforce.com/s/articleView?id=sf.flow_ref_elements_om_actions_adjust_ois_submit.htm&type=5
