First, this thread will lead us to a dark place, if it has not yet already.
Second, is the argument was Petain awful for collaborating with the Nazis and what he could have done more to be a better fella, or is the argument what Petain accomplished during World War One outweighs his collaboration guilt? The reason I ask, is that the OP seems to specifically hone in on the first part, and yet more than half of those "defending" Petain in this thread are citing his WWI contributions. Is the thread about Petain's legacy overall, or is it about what Petain did during Occupation?
Because, Heck, if we're talking overall legacy, then (in my view) Benedict Arnold's contribution at the Battle of Saratoga to the American Independence far outweighed anything he did to help the British once he turned and, gosh darn it, let's lay a stars-and-stripes wreath on his tombstone and pour a banquet beer on the curb for one lost "patriot."
Last, German occupation policies during World War II were subject to the treatment of locals per the idiotic Nazi creed, geographic location, the tides of war and the whims of the local satraps. "Marianne in Chains" is a decent book, in my view, in explaining how the attitudes of the German occupiers were restrained due to the age, educational background and worldview of most of the men in charge of the Occupation. All of this is to say, I don't buy, for one New York minute, the idea that Petain helped France (Vichy or Occupied) avoid a much more terrible fate had he not collaborated. My view. Opinion. Not fact. But that the line I draw in the sand there. I got zero sympathy for Petain, because France was not Ukraine and the hard and awful choices made by people in Kiev who then had to live with their choices for the rest of their lives and the lives of their child and their children's children is not something Petain ever had to face. "Collaboration" is a nuanced subject, but it loses a lot of its nuance the further West in Europe you travel. Once again, just one man's view.