I think there's a good chance he'd enjoy it. He's growing up in a world that his father, Naruto, had a huge impact on. Fanfictions can offer different views on Naruto's adventures, and Boruto might be curious to see how others saw his father's journey. Also, fanfictions might have some interesting new characters or plotlines that could capture his attention, even if they're not part of the official canon.
It depends on Boruto's personality. If he's the type who likes to explore different ideas and perspectives, then he would probably enjoy reading Naruto fanfiction. He could find some really cool and unique takes on the story he already knows so well. But if he's more of a traditionalist and only wants to focus on the official story, he might not be into it.