Combine the blueberries, coconut sugar, and lemon juice in a small pan on the stove. Cook on medium (4-6) heat for 5-10 minutes, then allow to simmer until the mixture reduces and thickens.
Add chia seeds to the mixture, whisk until well-combined. Allow to sit and thicken.
Place thawed phyllo dough on a sheet of parchment paper. Cut sheet into 6 squares (once lengthwise and then cut the two long strips into thirds). Transfer parchment paper with the dough to a large baking sheet.
Place a large spoonful of the cooled filling into the lower corner of one phyllo pastry square and brush the edges with coconut oil. Fold the opposite corner over into a triangle to seal.
Brush each turnover with more coconut oil and bake for 12-15 minutes, until golden brown. Check halfway through baking and turn the pan around if one side is browning faster than the other.
While the turnovers cool, whisk the glaze ingredients in a small bowl. The mixture should be thick, not runny; if needed, add more powdered sugar or plant-based milk.
Drizzle glaze over each phyllo turnover and serve. Makes 6 turnovers.