PayPal ShipStation has all USPS FC shipping converting to Ground Advantage also. If you have presets, you can easily update the USPS FC ones to the USPS Ground Advantage.
Anyone looking to get the $100 included insurance coverage with USPS Ground Advantage on Amazon will need to wait or purchase through another service (like PayPal or any other service that has already updated). Buying a label on Amazon will print out as USPS FCP and therefore will not have the included $100 insurance coverage as USPS will see it as a prior July 9, 2023 label purchase which did not include such service. Amazon may be slow to change since USPS will still accept USPS FCP labels until September 30, 2023.