No GPS in SCIFs. Agree ntp would be great. Also I’d prefer a way to manually switch between a fixed set of time zone, or even just showing UTC always as an option.
If you have a special project need, you might be able to get one-way IRIG time signal on fiber with guard boxes at both ends. There's really no technical reason why you couldn't do analog GPS baseband over fiber, but you do need approved equipment at both ends for policy reasons. (certified for no backflow)
There's other types of environments where you isolated users like SCIFs or really anything airgapped.
Hell: that would convince me to buy one that for my house.