Greetings!
Yeah, regardless of whatever kind of government a nation-state has--or in the case of France having a "Republic"--mere citizenship doesn't make you FRENCH.
French people are a distinctive blood, ethnic group, language, and culture. Just as if you were to move to Japan; learn the Japanese language; embrace Japanese culture. You might be made or classified as a Japanese Citizen--but none of that would suffice to make you *Japanese*
Really, virtually all nation-states are ethno-states, except for America. Russia, England, France, Germany, Japan, China, Mexico, Brazil, Mali, Kenya, and on and on. French are a distinct people just like Japanese.
Semper Fidelis,
SHARK