In a large mixing bowl, combine the flour, salt, sugar, and baking powder. Add cubed cold butter and use your fingers to work it into the flour, coating the butter well and breaking it into walnut-sized pieces as you go.
Fry the bacon until crispy and set aside to cool and drain on a sheet of paper towel. Roughly chop or crumble with your fingers. Chop the scallions and crumble the goat cheese. Add bacon, scallions, and goat cheese to flour mixture and stir to combine, then add the buttermilk and mix until a shaggy dough forms.
Transfer the dough to a floured work surface and shape into a disk, approximately 7 in./17 cm in diameter. If you have time, wrap the dough in plastic and chill for 1 hr. before proceeding for best results. Meanwhile, preheat the oven to 425°F/220°C, then use a dough cutter or knife to cut dough into 8 triangles and transfer to a parchment-lined baking sheet.
Brush the scones with more buttermilk and sprinkle with flaky sea salt. Bake for approx. 15 - 20 min., or until golden brown. Enjoy warm or at room temperature.