https://www.cnet.com/news/red-dead-redemption-2-has-a-companion-app-heres-what-it-does/

You can use the app to read the journal of the game's new hero, Arthur Morgan. Having the app also means you can remove the heads-up display from your TV when you're playing the game and still have Arthur's stats on hand. That gives you an even clearer look at the game's beautiful environment and vistas so that you're not constantly checking up on your health and hunger.

Seriously, just look at that view.