hi @TC13 Not sure if you can find a working solution for this or not. But if you are using USPS and want to implement conditional free shipping for one of the USPS services then I think I have a solution for you. It would require our Multi-Carrier Shipping Label app and the capped dollar amount.
You would be required to connect your USPS account within the app to display shipping rates. You will be able to set up a conditional rule that will provide a 100% discount on the USPS services of your preference.