Fulfillable location ID in Order API

@Gregarican In our case we have 2 locations. Whenever a new order arrives, shopify is automatically assigning the location to be used for fulfillment which is great. However, we want to get this information using REST or GraphQL, wow do we do that? Also unlike @PatrickWatzeels we are not getting the drop down to update the location, is there some setting we need to do for this?