Use old-fashioned oats for a thick texture. The quick-cooking kind can get too mushy.
In a large bowl, stir together oats, buttermilk, milk, syrup, vanilla and cinnamon. Divide between 2 2-cup-capacity containers. Cover and refrigerate for at least 7 hours or overnight.
Preheat oven to 350°F. Spread pecans on a small baking sheet and bake, stirring once, until toasted and fragrant, 8 to 10 minutes. Transfer to a small bowl and let cool.
In a small bowl, stir together fruit and lemon juice; divide between 2 small containers. Cover and refrigerate. Just before serving, stir oats mixture and top with fruit and nuts.