Since the RP2040 uses external flash you can pre-program the flash chips before they even get soldered on to the board. Other standard methods still work like

Since the RP2040 uses external flash you can pre-program the flash chips before they even get soldered on to the board. Other standard methods still work like breaking out the debug pins to some spot on your PCB so you can quickly "pogo flash" it as part of an assembly process.