You don’t need to worry about Elias and Xavier - the former very popular, the latter not that unusual - he’ll be called Eli or Xav day to day.
Yann is totally inoffensive
Florian and Etienne do sound feminine in English so avoid those.
Fabian, Lucian, Jules, Justin, Julian, Louis, Hugo, Alexander, Maxim, Nicolas, Gabriel, Raphael, Lucas, Marcus, Victor, Blaise, Damien, Henri, Leon, Raoul, Philippe, Ronan.. all work fine
Obvs w French spelling - Lucien etc, If you want