Of course tri. is canon.
Not knowing anything else about the story at the moment, I’m currently very invested in the idea that they are both slightly lost and don’t really know where they want to go from here.
I think Yamato may have some vague ideas about space, but maybe he isn’t ready to admit it — even to himself. Becoming an astronaut seems a really unlikely ambition. Going to grad school is a good way of opening his horizons while not committing to a career just yet. He’s interested in different things but it doesn’t seem like the sort of person who would settle for a conventional, boring job or waste time on something he isn’t 100% passionate about. So I could see him coming to the point where he has to face this wild dream of his and decide that he wants to go after it.
Sora going into the family business right after university makes sense but, at the same time, it’s the safe choice. I don’t doubt she likes Ikebana and is invested in preserving the family legacy, but at the same time, you get the impression that it would be nice for her to go in a bolder direction, and do something for herself. This brings me back to the scene in tri. where she won’t admit even to Piyomon what her future dream is. Something tells me she wouldn’t be hiding this dream if it was simply following on her mum’s steps. So I really think deep inside she wishes for something more, but maybe isn’t brave enough to pursue it (yet).
If only there was someone out there they could confide in and who could help push them in the right direction 🤔
I don’t think they’re a couple yet... But I think it would be cool if there was a connection between them deciding to pursue their Epilogue careers and them realising they should be together.