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.
It's possible that Naruto could meet some legendary Pokemon in this fanfiction. Since he has found an egg, it could be related to a very special or powerful Pokemon. Legendary Pokemon often have important roles in the Pokemon world, so they might show up to check on the egg or to guide Naruto in taking care of it. This would be a really exciting encounter for Naruto as he's used to dealing with powerful ninja abilities and now he has to deal with something completely different from the Pokemon world.
Well, Naruto might first be really confused about the strange Pokemon egg. He could try to figure out what it is and where it came from. Maybe he'd think it's some kind of new ninja tool at first.
Iruka could help. He's always been there for Naruto. He might know some old tales about mysterious eggs and give Naruto some useful tips.
He might meet an old Pokémon expert who gives him tips on hatching the egg.
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.
Well, Naruto might take the egg to his home and try to figure out what kind of creature is inside. Maybe he'd ask Kakashi for advice on how to take care of it.
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.
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.
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 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.