nobody would send a military vehicle (manned or drone) without initializing a proper clock, the replays would be stale.
There's a reason GPS satellites are used as reference clock for PPS, PTP and NTP. A naval vessel you could carry a Rubidium clock on, I guess. But on ground vehicles or mobile receivers... nope.
[ed.: OCXOs aren't that large, 1cm^3 box ballpark, too large* for a smartphone or laptop but not a problem on larger quadcopters, cars or military radio equipment. And 1ppm is long term drift, you can try compensating a bit beyond that, so - I guess it's a question of spending the money and energy** on OCXOs.
* thick specifically, can't easily be made thin AFAIK
** the first O there is Oven - roughly 0.5W continuous draw.]
Are you confident in these numbers? They add up to 52 minutes of drift/year.
Good modern quartz watches specify 5 seconds/year drift, almost 3 orders of magnitude better.
The difference with a quartz watch is that it's factory calibrated with the load capacitance on the crystal, and that it's a 32768Hz tuning fork. For a variety of reasons, generating higher frequency clocks off 32768Hz is... "annoying" (huge PLL ratio, very slow feedback loop step), and typical crystals in the 10-100MHz range are just less precise and thermally stable. (Not sure why, I'm not an oscillator manufacturer...)
(NB: you can of course correct for initial deviation in software. The actual problem is stability over temperature.)
Ed.: https://www.digikey.com/en/products/filter/crystals/171 (or, in the hopes the filter on the link works, https://www.digikey.com/en/products/filter/crystals/171?s=N4... ) - look at the options and prevalence for frequency stability & tolerance.
Ed.2: a wristwatch also benefits from being kept at constant-ish body temperature.
I think most quarts watches oscillate at 32 kHz = 2^15 Hz, high precision quartz watches at 8.4 MHz = 2^23 Hz.
> The actual problem is stability over temperature
Apparently, designers of these watches compensating for that somehow: https://en.wikipedia.org/wiki/Quartz_clock#Thermal_compensat...
> benefits from being kept at constant-ish body temperature
Some people take off their watches every day before going to sleep.
These high-end quartz oscillators are probably too expensive to use in commodity computers. Still, the cost shouldn’t look too bad when compared to a price or an airplane, marine vessel, or most military equipment.
(GPS sync is a question of nanoseconds.)