To me, Aang shaving his head symbolizes his new direction in life he’s going for after the invasion. He’s ready for everyone to know that the avatar is alive!
/r/TheLastAirbender: The Last Airbender - The subreddit for fans of Avatar: The Last Airbender, The Legend of Korra, the comics, the upcoming Avatar Studios animated movie and other projects, novels, games, and all other Avatar content. - November 9, 2022 - 18:45