You're getting this wrong.
Nobody considers Brittany is anything special except the Bretons, its inhabitants.
ALL French regions have their own culture, which includes a regional language.
People from Brittany don't have a distinct national identity, they're French, Brittany is just one of the few regions in France where the sentiment of regional identity is still relatively strong, like in Corsica or in the Basque country.
So no, it isn't comparable to Wales.
French people as a whole don't have anything against Brittany (though they think the weather is crap), but they don't understand why the Bretons think they're so special, because they aren't.
Personally, I live in Provence, here too we have our own culture and our own language, yet we don't consider Provence to be somehow more unique than the other regions of France.