This kind of in-universe material would probably work really well in getting across the sort of piece-meal way a lot of superhero media works best in. You could tether it in the reactions of people and the world and have the feeling of there being a larger history in the background of the character, without having to go through the enormous backlog of comic-book history.
Superman is the character this would be the smoothest to pull off with, due to his global influence in-world, and wide-spread imaginery in real life. But it could likely work with others too. A documentary showing the effects of Batman on Gotham, or the evolving public perspection of the Hulk would be so cool to watch too.
The news montage sequence from Batman Vs Superman remains, to this day, one of my favorite three minutes of superhero fiction