The US military is working on a device that can use stars to determine location even during the day.
They already developed a device that could do that in the 60s, but it was quite large:
https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Astro...
https://timeandnavigation.si.edu/multimedia-asset/nortronics...
Do you have a source for the one you say they're working on? Is more portable or hand-held?
However, stars are (to the nearest approximation) point sources. If you use a telescope and zoom in to the star, then you can spread the atmosphere brightness over a large area while concentrating the starlight into a very small area, which means you can see stars during the day. Couple that with a reasonable level of high dynamic range sensor and integration over time, and it would be quite possible to observe the positions of a load of stars during the day.