I think Naruto. Even though he's not one of the original Hokages, as Sarada's father, he has a deep understanding of Sarada. He could give her the most practical advice on how to face challenges, both in terms of strength improvement and mental growth.
Sarada would probably be in awe. She's always been interested in the history of the village. She'd be excited to see the First Hokage in action and learn about the early days of the Hidden Leaf. But she'd also be a bit out of place, with her modern - day ninja skills and knowledge.
Sarada might be initially shocked and sad. She loves both her parents, and the divorce would be a huge blow to her. She could become withdrawn for a while, not wanting to talk to her friends about it.
Perhaps a perk is the ability to shape the future of the ninja world. As Hokage, one can inspire the younger generation of ninjas. They can create new ninja academies or training programs. They also have the power to pardon or punish ninjas according to their deeds, which helps in maintaining law and order in the village.
Sasuke could also be a possibility for the 6th Hokage in the fanfic. He has grown stronger over the years and his unique perspective on the ninja world could bring new ideas to the leadership of the Hidden Leaf. He might start off as a controversial choice but prove himself through his actions in protecting the village and making tough decisions.
Sasuke could be an alternative. He has strong ninja skills and a deep understanding of the ninja world. His experiences have made him grow into a very capable person, and his Sharingan gives him an edge in combat and strategic planning.
Itachi would probably be very calm and composed. He might see Sarada as a symbol of the new generation of ninjas in the village. He could be gentle with her, perhaps sensing her potential and her desire to grow as a ninja.