Honestly, aside from BioShock, Red Dead Redemption 1 and 2 might be the only videogame adaptation that I would actually be interested in watching. Or better yet, a television series.
Not a movie, that would be impossible. Potentially a multi-season show like the Last of Us could work, but I think a lot of the plot would have to change to be more linear (a lot of RDR2 is just side missions and plot-irrelevant stuff).
They would have to pick the storyline, director, and cast very carefully because Red Dead Redemption is such a beautiful work of art that one thing off could completely ruin the experience. The public has developed such a high expectation of the Red Dead series. They did Red Dead Redemption: The Man From Blackwater, which was the 30 minute movie made with the game engine, and that turned out decent for it's time.
Or instead of a live-action movie/series, maybe they could make it animated and do with Red Dead Redemption what they did with League of Legends and Arcane. Best show ever in my opinion.
Animated could work, but for a western game heavily reliant of realism and its cinematography, I think live action show would be the best method to go.
The reason I chose maybe is that if it turns out bad or not live up to its expectations, then not only the movie, but maybe even the franchise might just fall off.