This page of the guide to Star Wars Jedi: Fallen Order answers two quite important questions - are there any choices and is there more than one ending.
In Star Wars Jedi: Fallen Order, the player doesn't make any choices affecting the storyline. Dialog options can appear during some of the conversations but they have no meaning and they don't affect the outcome of the conversation or the attitude of the character towards the main character. You can ignore the dialog options - if you don't press any buttons, the game will choose the answer for you.
Star Wars Jedi: Fallen Order has only one ending. You can't change the course of the main plot. The game offers, of course, a lot of additional exploration or even fights with optional bosses, but none of these additional elements are connected to the main plot.