> We've had clocks for decades that synchronize to atomic time sources accurate to within 1 second over 100 million years that automatically correct for daylight savings time that do it all by just listening to publicly available radio broadcasts, no wi-fi or information harvesting required.

In the US we have:

https://en.m.wikipedia.org/wiki/WWVB

> WWVB is a time signal radio station near Fort Collins, Colorado and is operated by the National Institute of Standards and Technology (NIST).[1] Most radio-controlled clocks in North America[2] use WWVB's transmissions to set the correct time.