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.
In this fanfiction, Naruto could also meet any siblings he might have had if things had been different. They could bond over their shared bloodline and have some fun adventures together, exploring their family's secrets and powers.
Besides his parents, Naruto might also meet his extended family. Maybe some distant relatives who were also ninjas and they could share stories about the family's ninja heritage. He could also meet his ancestors who had a great influence on the Uzumaki clan.
It could be Sakura. She has been Naruto's friend for a long time. She would be excited to see him return. They might share a heartfelt reunion, and Sakura could tell Naruto about the medical advancements in the realm while also asking about his adventures away.
He would most likely meet his parents, Minato and Kushina.
In this fanfiction, Naruto might finally have an emotional reunion with his parents. He could share all his adventures, growth, and the pain he endured. They would likely be proud of how he became a great ninja.
He might meet Iruka first. Iruka was always like a father figure to Naruto, and it would be a very heartwarming reunion. Iruka would probably be one of the first people to welcome Naruto back with open arms.
He might meet an old acquaintance who is also alone. They could share their stories and perhaps find some comfort in each other's company.
Naruto could also meet the previous Hokages in their prime. He could learn from them directly and perhaps even influence their decisions. For example, he might be able to convince the First Hokage to handle the Uchiha clan's situation differently, which could have a huge impact on the future (or in this case, the future that Naruto comes from).
Naruto would meet his younger self. This would be a really strange situation. He could also meet all the important shinobi from the past. For example, the First and Second Hokage. He might have a chance to learn from them directly, instead of just hearing about them in stories. Additionally, he could meet some of the characters who were only mentioned in passing in the original story but had a big influence in the past.
There could be new characters created specifically for this fanfiction. Maybe a young Suna shinobi who becomes Naruto's guide in Suna, showing him around the village and introducing him to the local way of life.
There's a chance he could meet an older and wiser Kakashi. Kakashi might have new insights and stories to share with Naruto from all the years that have passed. And also, he could run into future shinobi who look up to him as a legend from the past.
Naruto might meet Itachi in heaven. Itachi could finally reveal all the secrets and the true intentions behind his actions to Naruto. And they could become true friends without any misunderstandings. Additionally, Naruto could also meet Neji, and they would talk about how the ninja world has changed since Neji's sacrifice.