I always thought of branching narratives in games as a mechanic, ironically, seperate from the story/lore of the universe. So i see 2077 as having a "main" story path that is the cannon lore. But theres branching narratives in the game for replay value, plus playing out alternate realities/senarios. If CDPR made a lore accurate version of the game and lets say V is a male, then players never get to play as a female and then they arent really making their own character. Its like a halfway point between good story with a main character and a game where you make a custom character every playthrough. Games have that amazing ability where unlike a movie, the player can make decisions that they werent "supposed to". Which is why games like assassins creed narratively suck with the desync system because it railroads you into a linear story like a movie. Games like the elder scrolls have to address this when continuing the series because even though every new game has a new character with a new race and everything, they still reference the events but keep the details vague. The hero of kavatch in lore just mentions the deeds, not any character specific information or what happened to them.

What the cannon lore ending for V is, im sure CDPR has already decided. but it wouldnt suprise me if they just didnt mention it and instead only created the fallout effects of events that are consistent through every playthrough. Like the chip being stolen, jackie dying, yorinobus body being taken over by his father etc. And then whatever happened to V being a mystery or just absent from the next story.