This really only affects compasses. For centuries, people have known that the compass does not point to the true north, but a bit off, with the angle depending on your position on the planet - potentially huge, if you are very far north/south, but that people only learned laterz when they got there
Before the advent of modern technology, there were tables to correct for this effect. Now presumably (I do not have any device with such function personally) you can have a compass, say, in your smartphone and let an app do the correction for you - such app then needs to be updated more frequently as the movement of the magnetic pole speeds up.
I have not yet met a consumer navigation system that actually uses magnetic data for anything, simply because for that purpose, GPS is better. I can imagine people using an app for navigation while walking in nature, where you don't have roads to follow - insuch app you'd have a map and use the compass in the smartphone to tell you where to go. Then this would be affected, but 1. the precision of the bearing gotten this way is probably worse than the error caused by the shift.l an 2. once you start moving, the app will know which way you go from the change of your GPS location and can correct from it.
On the other hand I have no idea how for example ship and aircraft navigation works, I only know that flying has been really conservative in adoption of GPS (because it's not guaranteed to not stop working on a whim of the US Army) so they may be using compasses and have to adjust for this - and I am sure they will because they are really meticulous.