So, not this data exactly but broadly similar data (Japanese publications of differential GPS corrections) have been used to spot North Korean missile launches in the open source world.
has more info on that. Essentially the corrections for each satellite can give you a map of what the ionosphere looks like, and so having more satellites is better. If there were publicly available dGPS- or dGLONASS/dBeiDou etc. archives available in other countries it would make this even more useful. If China or Russia published these it would be very useful indeed for triangulating the flight path through the ionosphere.
https://www.armscontrolwonk.com/archive/1216884/detecting-mi...
has more info on that. Essentially the corrections for each satellite can give you a map of what the ionosphere looks like, and so having more satellites is better. If there were publicly available dGPS- or dGLONASS/dBeiDou etc. archives available in other countries it would make this even more useful. If China or Russia published these it would be very useful indeed for triangulating the flight path through the ionosphere.