Chinese enthusiasts asked the same question. They disassembled the iPhone 14 brought from the US and found that the new phones had a plastic plug instead of a SIM card tray.
As a result, they learned how to replace the middle frame of a smartphone (and in some cases just drilled a hole), after which it was possible to install a physical SIM card in American iPhones.
It is worth noting that this can be done at home with a crank. In this case, buying a smartphone in the United States will be quite profitable, as it is the only market where the price of the iPhone 14 has not risen.