Sakura would be heartbroken. She would probably blame herself for not being able to protect Naruto. She might also start to train harder to fill the void left by Naruto.
The other genin competitors would have a variety of reactions. Some might laugh at Naruto, thinking he's being foolish. However, others might be inspired by his boldness. The proctors of the Chunin Exams could be either strict and try to stop him if it violates any rules, or they could be lenient and see it as a creative form of self - expression. And Naruto's friends from the village would likely cheer him on, seeing it as just another one of Naruto's unique antics.
Sasuke would likely be intrigued. He has his own dark path to some extent. He might see Dark Naruto's departure as a bold move and wonder if he could have the same courage. At the same time, he might also be a bit envious that Naruto is able to break free in such a way while he is still tied to the village in some ways.
Perhaps in this fanfiction, Naruto is fatally injured in a fight during the Chunin Exams. He might sacrifice himself to save one of his friends. This would cause a great outpouring of grief from his friends and mentors. The village would also be in shock, and there could be a change in the power dynamics as his absence leaves a void.
For Hinata, it would be a crushing blow. She loved Naruto so much. She might withdraw into herself at first, overcome with grief. But then, she could find the strength within herself to carry on Naruto's legacy, especially for their son, Boruto (if in a post - Naruto - has - a - family scenario in the fanfiction). Shikamaru, being Naruto's friend, would feel a deep sense of loss. He would use his intelligence to try to figure out what led to Naruto's death and if there was any way to prevent it in hindsight. And the other members of the Leaf Village would be in a state of shock and mourning. Naruto was their hero, and his death would make them question their safety and future without him.
Sakura would be devastated. She has been Naruto's teammate for a long time. She might blame herself for not being able to save Naruto. She would probably become more withdrawn and focus all her energy on finding a way to bring Naruto back, even if it's impossible. Kakashi would be deeply saddened too. He has always seen Naruto as a special student. He would likely feel that he has failed as a teacher.
His friends would probably be very surprised. Shikamaru might be the first to raise an eyebrow, thinking Naruto is up to his usual unexpected antics. Sakura might be initially worried that Naruto is getting distracted from the real purpose of the Chunin exams. But as Naruto starts to play, they could end up being entertained and rooting for him.
At the start, Naruto might be a bit intimidated by Pakura. But as the story progresses, he would open up to her. They could form an unlikely alliance. Naruto would share his dreams of becoming Hokage with her, and Pakura would share her experiences as a shinobi. This interaction could help Naruto grow both as a person and as a ninja during the Chunin Exams.
The other genin would be in awe. They would see Naruto as an almost unbeatable force. Some might be scared, like those who are not used to seeing such a powerful display. For example, the weaker genin might feel completely outclassed.
The characters in 'Naruto' would be deeply affected if Naruto dies at birth in fanfiction. Jiraiya would be one of the most affected. He saw Naruto as his protege and the hope for the future. Without Naruto, Jiraiya might lose his enthusiasm for training and spreading his teachings. Tsunade would also be saddened as she had a connection to Naruto through her relationship with Jiraiya and Minato. The Rookie 9, Naruto's friends, would have a completely different dynamic. They might not form as tight a group without Naruto's energetic and positive influence. And the Sannin, as a whole, would have their relationships and legacies altered without Naruto in the picture.
The Chunin Exams' storyline would be completely different. Naruto could use his time - traveling knowledge to expose the plot of some of the enemy ninjas earlier. He could also team up with some unexpected characters during the exams. For example, he might form an alliance with Kabuto, but this time with the upper hand as he knows Kabuto's true motives. This would create a whole new set of alliances and rivalries within the Chunin Exams, making for a very different and exciting story.