If you can get a GPS fix (or a lat long to start), you can run an INS just as easily.
Of course, those have significantly less performance than the one you put in an airliner or ballistic missile.
As you mention yourself, its a question of good enough. You need to be a lot more accuracy to hit a city after a twenty minute sub-orbital coast, than to find the nearby trench. And yes, computer vision is used to correct for drift.
[1]: IMU's on DigiKey: https://www.digikey.com/en/products/filter/motion-sensors/im...