I understand that the Vichy government was essentially just a German puppet, but were there currents there who considered the independence of Southern France a good thing, particularly within the context of linguistic revivalism?
Whoa--that is an interesting question. I have not see anything on Occitan nationalism. I do know of Breton movements that attempted to ingratiate themselves to the German occupiers but were later disgraced. Occitan nationalism seemed to reemerge as a cultural force during the 1960s and '70s as part of the greater movement of regionalism in France (Bretons, Alsacians, Basques, Corsicans, and Occitans all developed movements, sometimes working together). I would imagine that regionalism would be seen as a threat by Pétain (who believed the concept of the patrie as a form of nationalism). I'll ask some colleagues who know a bit more about the Vichy era (I am a postwar specialist) to see if there is any known Occitan-Vichy connection.
Following up--talked to a colleague who specializes on Vichy and there was an active support of regionalism among Vichy officials but no high level Occitan separatists within the government. The recognition of the region as a political unit was given lip service by the creation of office of regional prefect in 1941 (under the Darlan administration) but no real reform was instituted despite the presence of regionalists (including Occitans but lots of Provençals) in the Vichy regime. Apparently, the Occitans who joined with the regime tried to distance themselves after the war despite ample evidence of their support for Pétain. I hope this helps!
Sources: Robert Paxton's classic Vichy France (1973) and Aviv Amit Regional Language Policy in France during World War II (2014).