One great true K9 training story is about a police dog named Max. Max was trained to detect drugs. Once, during a routine traffic stop, Max signaled that there were drugs in the vehicle. His training was so precise that he led the officers straight to the hidden compartment where the drugs were stashed.
A K9 named Rex was trained to assist the disabled. He could help his owner, who was in a wheelchair, by picking up items, opening doors, and even alerting when the owner needed medical attention. Rex was a great example of how K9s can be trained to be useful companions in special situations.
The story of the K-19 submarine has elements of truth, but it's likely that some details have been exaggerated or modified for the sake of the narrative. We can't know for certain how accurate it is in every aspect.