Rias herself could have a complex reaction. She might be hurt if she had developed feelings for Naruto. She could also be angry if she felt Naruto was leaving without a good reason or was abandoning her. But at the same time, she might understand if Naruto had a valid reason related to his own world or responsibilities. She would have to deal with the emotional fallout and also the practical implications of Naruto's departure for her group.
The characters close to Rias might be relieved. If they see Naruto as an outsider or a potential threat, his leaving would be a good thing for them. They would probably go back to their normal routines without Naruto's presence causing any disruptions. For example, some of Rias's devil comrades who are more traditional might not like Naruto's different ways and values.
On the other hand, those who have befriended Naruto would be sad. They might try to convince him to stay. If there are any characters who have come to respect Naruto for his strength and unique personality, they would feel a sense of loss. They might think that the group is losing an important asset. For instance, if there are other hybrids or those who understand Naruto's situation of being from a different world, they would be disappointed.
Sasuke might be conflicted. He has his own complex relationship with Naruto. Part of him might understand Naruto's reasons for leaving, but he could also be angry that Naruto didn't confide in him. Sakura would be worried sick. She has always cared about Naruto, and his leaving would leave a big hole in the team. Kakashi, on the other hand, would be disappointed but also respect Naruto's decision if he thought it was for a noble cause.
Sakura would be deeply affected. She has been Naruto's friend and teammate for a long time. His departure would make her feel guilty, thinking that she could have done something to prevent it. She might also worry about his safety out there alone.
Sasuke might initially be indifferent on the surface, but deep down he would feel a sense of loss. He has always had a rivalry with Naruto, and Naruto's departure would mean an end to that dynamic. Sakura would be devastated. She has grown to care about Naruto as a friend and teammate, and his leaving would leave a big hole in the team.
Sakura might be initially shocked and then start laughing uncontrollably. She would probably tease Naruto about it for a while. Sasuke, on the other hand, would likely just give a slightly raised eyebrow and then act as if it's not a big deal, but deep down he might be a bit amused. Kakashi would probably make a dry joke about it.
Naruto's reaction to the other members would be complex. He has a big heart, but being forced into the peerage would make him resentful at first. He'd see the other members as part of the system that forced him. But as he spends time with them, he'd start to notice their individual personalities. If there are any members who are outcasts or treated unfairly, he'd side with them. His own experiences of being an outsider in his village would make him empathetic. And when it comes to their powers, he'd be eager to learn how to counter them in case he ever needed to defend himself within the peerage.
Sakura would be shocked and immediately try to protect the villagers. She might use her medical ninjutsu to heal any injured villagers and then try to subdue Naruto. She would probably be very vocal about how Naruto's actions are wrong and try to bring him back to his senses.
Shikamaru and the others from the Rookie 9 would be shocked. They have always counted on Naruto to be there in Konoha. They would probably feel a sense of loss and also a bit of guilt, wondering if they could have done something to prevent Naruto from getting so tired of the village. They might try to find ways to get him back, while also respecting his decision if he is determined to leave.
Sasuke might be more understanding. Given his own experiences of leaving Konoha, he could respect Naruto's decision. However, he might also secretly plan to keep an eye on Naruto from afar to make sure he is safe.
Sakura would probably be very worried. She has always cared about Naruto deep down, so she might be constantly trying to find a way to bring him back. Kakashi, on the other hand, would likely understand Naruto's reasons to some extent. He might be sad but also respect Naruto's decision. As for Sasuke, if he is in the village at the time, he could be conflicted. He and Naruto have a complex relationship, and Naruto's leaving might make him realize how much Naruto actually means to him.
Some might be in shock. Naruto, regardless of being male or female in this fanfiction, has been a significant part of the village. People who have come to know her would be surprised that she would leave. They might start to question if there was something they could have done to prevent it.