You could also have pull up and monitor when it goes low if the serial is permanently attached and the pin is high but first character may be lost, which is still ok for console if you first press Enter and wait a bit.
For ds-d6 I went with first option so console was enabled when I plugged it into usb female attached to usb serial adapter.
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.
you can monitor RX pin with setWatch (with input pulldown) and when it goes up you reconfigure it as serial, I had it like this on DS-D6
https://gist.github.com/fanoush/ce461c73c299834bcb53a615721b5a2e#file-dsd6-js-L234
You could also have pull up and monitor when it goes low if the serial is permanently attached and the pin is high but first character may be lost, which is still ok for console if you first press Enter and wait a bit.
For ds-d6 I went with first option so console was enabled when I plugged it into usb female attached to usb serial adapter.