The main application would obviously be missiles and autonomous military drones. If you can use GPS - you should. It's crazy cheap and it doesn't accumulate errors over time. But in a war GPS can be jammed. This can't.
https://en.wikipedia.org/wiki/AGM-158_JASSM
> Guidance system: GPS, INS, IIR
By the time the small diameter bombs had been married to a rocket the Russians had effective and pervasive gps jamming and accuracy plummeted.
The older more expensive systems with ins like atacms maintained accuracy.
There are tricks to avoid most of the GPS jamming, long-distance drones use them (he said the evolution is crazy fast, every 3 months there's new techniques deployed) the traditional military systems can't be modified in 3 months so they are more vulnurable.
They are constantly changing the video and controlling frequencies, there is some AI appearing, a big change was flying signal repeaters, there are tethered flying drones with rolls of fibre for steering/video that are completely invulnurable to jamming. Often they also have cables for power, so they can stay in air forever.
But even in the cheapest drones there are ways to deal with it. For starters you shield the GPS from the bottom half-sphere, and you put 2 GPS receivers at opposite ends of the drone and compare the signals. Jammers are closer than sattelites, so the difference between the signals sampled 2 meters apart will be mostly the jamming, and then you can remove it.
It's not perfect, but it's good enough for the drones to hit the targets most of the time. And they obviously have cheap accelerometers, compass etc - which is basically INS, just less accurate. So it's sufficient to get by through the region with jamming, and to recognize when GPS is spoofed.