I think southerners or people in rural areas may use some variant but not straight Papa.
Wrong. But not surprised.
I'm Southern, never heard any Grandpa called Papa, no father called Papa or anything close to that. Mostly it's a northern thing. Or Hispanic.
My great grandparents were Momette and Popette. They were French. My Grandmother was Grandma, my Grandfather was Grandpa, my mother was Chee Chee, my father died very young so my kids never met him. My husband's mother and father were Maw and Paw, his Grandmother was Gram or Poopie, a childhood nickname. His Grandfather was asshole

He died before our kids were born. Mean old man. He went by Paw Paw.
Didn't Madonna call for her Papa not to preach ? Northern thing.