It's true what you said, in fact most of the players in the French National Team are naturalized from other countries. Personally, the egoism that is shown is not based on the origin of the player but rather on his star status at club level and individual fan base. The role of the coach and seniority is very important to reduce the attitude of fellow players on the field so that the final goal is to win the match. Didier Deschamps' squad in the Euro 2024 qualifiers was mostly made up of young players overall, otherwise only Giroud and Griezmann are over 30+.
Specifically, I would say that a player who is selfish above the average other players in the French squad is Mbappe, yes, I think it's natural because he is the main focus of the team. Maybe he will become a permanent captain to replace the role of Hugo Lloris who retired from the national team.
Most of the French players are born and brought up in France, and only a few are naturalized (although majority are of immigrant origin). So I don't think that it is an issue. I haven't noticed any team bonding issues with teams like England and Netherlands, although they are also having mostly immigrant squads. I am disappointed that despite having so many great players, France fails to perform well at major tournaments. They reached the final of 2022 Qatar world, but in the end it was a meek surrender to Lionel Messi's Argentina.