hi @Kristina_Sarma I am unsure if there is any way to do this without linking to a carrier. However, I do have a workaround for this. You will require your supplier’s carrier accounts and the Multi-Carrier Shipping Label app to link all those carrier accounts. Once done, you will be able to let customers add products to the cart and display shipping rates as charged by the suppliers on the Shopify checkout page.
Since your suppliers are shipping from Australia, I would guess they may be using carriers like Aus Post MyPost Business, FedEx, DHL, TNT, etc. The good part is the app supports the majority of these carriers and works together to display accurate rates all the time.