Snuggle had, indeed, an outstanding feat in mind.
She wanted Noctis to escort them to the Shadow Realm.
There was some merit to her idea, no doubt. After all, neither of them were familiar with the mortal realms and people who populated them — both the shadow and Snuggle were completely ignorant of their customs and traditions, let alone invisible undercurrents that ruled all human societies. They did not know what roads to take and which places to avoid, so they needed a guide.
Well… the shadow could probably find his way to the Realm of Death on his own, eventually. It was just that he would most likely leave a trail of devastation in his wake, which Snuggle wanted to avoid.
Noctis, meanwhile, was not only knowledgeable about the world outside the shadow's lightless kingdom, but also held quite a lofty status among humans — his fame and background alone could open many doors for them. And he would probably know where to go, as well.
