Chop the peaches and apple into bite-sized pieces and add them to the bottom of a large pitcher. Sprinkle them with sugar and stir. Let them stand for 20 minutes at room temperature.
After 20 minutes, pour in the white wine and brandy. Add the fresh mint and thinly sliced lemon rounds. Stir and refrigerate for 1 to 4 hours. (Don’t go beyond 4 hours or the fruit texture starts to degrade.)
Pour the white sangria into ice-filled glasses and top with a splash of sparkling water (if desired). Add fruit to each glass, preferably on long skewers for easy snacking.