https://macnotes.wordpress.com/2022/01/14/device-specific-parameters-for-jamf-pro-script-policies/

Custom Schema :

Preference Domain : com.my.script

{
  "title": "My Script Settings",
  "description": "Settings for my script",
  "properties": {
    "jamf_mac_username": {
      "title": "Username",
      "description": "The Jamf device owner",
      "property_order": 10,
      "type": "string"
    },
    "jamf_pro_id": {
      "title": "JSSID",
      "description": "Jamf Pro ID",
      "property_order": 10,
      "type": "string"
    },
    "jamf_mac_fullname": {
      "title": "FULLNAME",
      "description": "Full Name",
      "property_order": 10,
      "type": "string"
    }
  }
}

Sample script :

#!/bin/bash

# Ref : https://macnotes.wordpress.com/2022/01/14/device-specific-parameters-for-jamf-pro-script-policies/

preference_path='/Library/Managed Preferences/com.my.script.plist'
preference_key='jamf_mac_username'

jamf_mac_username=$(defaults read "${preference_path}" "${preference_key}")
touch "/Users/Shared/READ ME ${jam_mac_username}!.txt"