Real time clock on Pico (rev 1.4)

That's right, yes! Definitely try without the capacitors first, as they can be a pain to solder :) If you have a hot air gun then the crystal should be pretty easy to add though.

To test, just run the following magic code more than 5 seconds after startup:

(function() {
  console.log("LSEON",peek32(1073887344)&1);
  console.log("LSERDY",peek32(1073887344)&2);
  console.log("LSION",peek32(1073887348)&1);
  console.log("LSIRDY",peek32(1073887348)&2);
  console.log(["NONE","LSE","LSI","HSE"][((peek32(1073887344)&768)>>8)]);
  console.log("RTCEN",!!peek32(1073887344)&32768);
  // RTC subsecond
  console.log("Subsecond:", peek32(0x40002828));
})();

It'll say LSI without a crystal (low speed internal), and LSE with one (low speed external)