For me OneDrive “memories” are from my wallpaper folder or Xbox screenshots.
Google “memories” are food diary photos (on days when my food budget is spent, Google loves to show me photos of the massive pizzas I ate years ago, because it knows) or random sunsets. (Except for that photo collage with cheery music from my grandma’s funeral. Why did it have to do that specifically. Just asking.)
Debian user here. Checks out.
Though I use Windows (and Debian WSL) as desktop daily. The fact that I mostly drink instant coffee is possibly related.