Not even thousands

Not even hundreds

Try 31

You're literally off by a factor of 3225

Hundred of thousands of satellites? Are you on mushrooms or something?

Wait until you hear about compasses and maps!

It’ll get scuttled by the intelligence community so they can use it in the intelligence community.

You think there are hundreds of thousands of GPS satellites in orbit?

*Cant be Non-magnetically hacked

Don't these fields fluctuate in some currently not understood way?

It's going to be missiles again isn't it?

Two issues I have with the presentation:

A magnetic field is an external signal - the Earth's magnetic field is actually incredibly weak...

10x better performance than GNSS ... positioning accuracy of 1 nautical mile. Cheap old school handheld GPS out in the woods was accurate better than 10 feet most of the time, so what in this performance is 10x better? 10x more resistant to jamming? Seems like it should be completely impervious to jamming. 1 nm accuracy is useful, but hardly better performance.

As long as you keep it below 88 miles per hour you'll be fine.

this article is better written:

https://science.report/discover/quantum-gravimeter-demonstrates-gps-free-navigation-in-coral-sea-trial-86654/

it maintained bounded position accuracy within 1 nautical mile over an 83-kilometer trajectory. This performance, achieved without access to satellite navigation, represents a more than tenfold improvement over standard navigation-grade inertial backup systems under similar conditions.

That's comparable to what a skilled navigator can do with a sextant and chronometer. That's more than enough accuracy to cross the ocean and get close enough to the port that you can see it.

If I were in the middle of the ocean I couldn't find my location within 100 nautical miles without GPS so I'm pretty impressed

High-end dual-frequency receivers ($$$) can do this, yes. But the earth's magnetic field is not controlled by any government or military entities. This is pretty big

Yes and no. They often use GPS assisted by beacons. Those beacons are often set up using both high quality GPS but also surveying tools, and you might have seen markers in the ground on cities which was placed using very well calibrated tools so it has a well known very precise precision. Those beacons are easier to track for other machinery because they are so much closer so the radio signal is much clearer and angular precision is much better