"Naoned", that is to say Nantes, has never been Breton speaking. Same for Rennes. They were part of the March of Brittany set up to specifically defend against the Bretons, but they successfully annexed it in the commotion left by the Norsemen. The court of Brittany became French-speaking when it moved there.

Also, nobody in Marseille writes "Marselha", If you want to do some out of place indigenous rights dog whistling, the proper orthography in Provencal is Marsiho. Normalized Occitan is of ill repute in Provence, and so is the associated Occitanism.