>>938563509 (OP)
I'd watch a film on the reign of Louis the Pious. A Charlemagne film would probably be easier and make more sense, but Louis's lifelong guilt of conscious and public self-debasements for atonement would, I think, make for a fantastic and interesting psychological drama/character study.
>>938574527
Might work better as a TV series. You'd call it "The Carolingians," the first season (or few seasons) would cover Charlemagne, then there would be a season or half season on Louis the Pious, and then you'd end with the mess of succession after Louis's death.