Real time clock on Pico (rev 1.4)

Ahh, yeah - it's in the schematic, and there are pads for it (right at the end of the board), but it isn't fitted.

You can fit one if you want, and it'll be automatically detected and used. In reality the capacitor values should be under 4pF, and are so small they can actually be left off without any real problems. You just need an ABS06-107 crystal. The 107 bit is important though.

The Espruino WiFi does have the crystal installed, so if you wanted then that is another option as well.