GPS isn't too hard, either.

The receivers are inexpensive ($5-$10 for the kind of accuracy that's useful here) and it's not hard to parse the NMEA strings and PPS they output into a spooky-accurate internal clock. It only takes a few connections and an antenna to integrate GPS into an MCU like an ESP (or an SBC like a Raspberry Pi or a whatever).

Like, really: The hardware is ridiculously easy.

The only difficult part is the code. But as we can see from this posting, the clock-driving bits are already written and are available for use.

Just graft in the GPS parts instead of the NTP parts, add your DST/location rules if you really must (hint: that part is harder than it sounds), and send it.

(And if the code still seems arduous, then remember: This is the kind of work that a reasonably-focused person who is armed with a decent bot can put together over a cup of coffee or two, even if they don't speak C. It may be popular here to poo-poo the bot here, but it's completely OK to get some help. Don't let pride get in the way of having fun, learning things, and building neat stuff.

The tailor doesn't lament the invention of the cotton gin.)