He could meet the previous Hokages. Since the library is infinite, there might be records or even some kind of spiritual manifestation of them. They could guide Naruto further in his journey.
In the infinite library, Naruto might encounter strange and mysterious beings. Maybe there are guardians of the library who have been there for centuries. These beings could test Naruto's worthiness to access certain parts of the library. He could also meet characters from other ninja villages that he has never interacted with before, and through them, gain new perspectives on the ninja world.
He might meet the spirit of an ancient ninja who was the keeper of the library. This spirit could guide Naruto through the library and teach him things that no one else in the present day knows.
Naruto might run into a group of rogue ninjas who are using the bunker as their hideout. This would lead to a confrontation where Naruto has to use his skills to defeat them and protect the village from their potential threats.
Naruto could encounter a group of rogue ninja who are also after the treasures in the Uzumaki temple. Then he'd have to fight them off to protect the temple and its secrets.
He might meet an old hermit who has been guarding the temple for centuries. The hermit could have valuable knowledge about Naruto's parents or some secret ninja arts.
He might meet an ancient sage who has been sleeping in the ruins for centuries. This sage could have a vast amount of knowledge about chakra and the ninja arts that Naruto could learn from.
He might meet the spirit of an ancient ninja.
Perhaps Naruto would use the infinite library to understand his enemies better. He could study the weaknesses of his foes by finding information about their clans or fighting styles. Also, he might find books that could help him train his friends more effectively. The library could be a source of great power for Naruto, not just in terms of combat skills but also in terms of wisdom and leadership.
He might meet Hinata. She is kind - hearted and would surely be interested in the puppy. She could offer to help Naruto take care of it, like making a little bed for the puppy.
He would most likely meet his father, Minato Namikaze, and his mother, Kushina Uzumaki. These are the two main family members he never really got to know growing up.
He could meet some Pokemon trainers. They might come looking for the lost Pokemon egg and Naruto would have to decide whether to give it back or keep it.