I guess there might be some misunderstanding on the question. A "biopic" is a biographical picture/film.
While SPR is a masterpeice its not biographical in the sense that it is talking about a real person "James Francis Ryan". The plot was loosely based on the Niland brothers. Two of the four were dead, the third presumed dead (actually a POW), and the 4th was discharged. The two that lived died in the 1980s.
To Hell and Back is not only a biographical film, but an autobiographical film. Because A) Audie looked like he was 16 well into his adult life, and B) who else is gonna play him? seriously. Imagine being at a casting call and theres a dude sitting there, covered in 20 lbs of decorations and the MoH around his neck, not needing to recite lines cuz he wrote em. lol.
Then there is Black Hawk Down and We Were Soldiers, there are countless military films too like Midway and, gag, Pearl Harbor that focus on events in the war, they may even tell it from a protagonist's perspective. But they arent biographical because the movie's focus is about the battle, not one guy over the course of many years. Does that make sense?