So, as far as this "canon" stuff is concerned, there is technically a canon series of events that happen regardless of player choice, and whilst all the moments and events based on player choices are canon in the sense that DPC made them and they're part of the story, they form part of each player's own individual canon story where they play out these events in their own way.
Take Sage, for example. The canon moments with her are as such:
- Meeting her in the cafeteria
- Meeting her the next day
- Getting the guitar back from her
- Seeing her at the DIK party
- Spying on Chad for her and then meeting her in her dorm room
- Sparring training with her
- Chatting with her in the Prep mansion
These all happen regardless of whether people choose to pursue Sage or not, therefore players who choose to give Sage guitar lessons and progress to FWB with her get a certain series of events which then become their canon version of the story.
However, whilst this game does have canon events which happen for everyone regardless of the path they're on, we can't really say that there is a definitive canon version here because the story is going to be whatever the player chooses to make it. Even Quinn's drug business will surely enter the MC's sphere at some point and there will likely be choices to be made that will affect her and it, thus affecting its trajectory, so it too will not have any kind of fixed "canon" path.