Well, I beat Ganon and did all the memories in BotW today.
In that order, because apparently I'm dumb. I kind of thought as I was playing that maybe I should go back to Impa first, but that's so flow-breaking when you're already in the castle, so I just finished Ganon. Good thing there's YouTube though; when I felt like the ending was a little lacking I just looked it up and sure enough there is a "true" ending.