Espruino generally expects all the devices to be continuous (Serial1,2,3,4,5,6) - but on the F401 parts they're not. As the Pico doesn't have Serial6 available (it clashes with USB) I'm in no rush to add support I'm afraid.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Serial6 isn't supported on the F401.
Espruino generally expects all the devices to be continuous (Serial1,2,3,4,5,6) - but on the F401 parts they're not. As the Pico doesn't have Serial6 available (it clashes with USB) I'm in no rush to add support I'm afraid.