Preheat the oven to 425°F (220°C) and line a baking sheet with parchment paper.
In a mixing bowl, stir together the sourdough discard, warm water, and sugar until smooth.
Add the flour, baking soda, and salt. Mix until the dough starts to come together.
Turn the dough onto a lightly floured surface and knead for 3 to 4 minutes, until smooth and slightly elastic.
Pinch off small pieces of dough and roll them into bite-sized balls, about 1 inch each. Place them on the prepared baking sheet.
Bring a large pot of water to a gentle boil. Drop a few dough balls into the water at a time and boil for 30 seconds. Remove with a slotted spoon and place them back on the baking sheet.
Sprinkle the tops with flaky sea salt.
Bake the Sourdough Discard Pretzel Bites for 12 to 15 minutes, until golden brown and puffed.
Brush with melted butter right after baking if desired, then serve warm.