There is a special type of field that lets administrators select an item - or multiple items - from Organizer.
When the item is picked, the administrator will see the item's display name (specifically, the name determined using the label_format_for_picked_items property on the Organizer Panel), but the id of the item will be stored in the field.
If you allow an administrator to select multiple items by setting the multiple_select property, their ids will appear in a comma-separated list.
To make a pick items field work, you need to provide a target path in Organizer. This needs to be a tag path (i.e. the direct route to the panel) and not a navigation path.
You will also need to limit the administrator's navigation using the path, min_path, max_path and disallow_refiners_looping_on_min_path properties as needed.
pick_items: