Cut scallions crosswise into thirds. Julienne the sections lengthwise, keeping white/pale green parts separate from the dark green parts.
Put oil and white/pale green portions of the scallions in a cold wok or deep skillet. Set heat to medium-low and toss scallions to coat with oil. When scallions begin to sizzle, add dark green portions and cook, stirring frequently, letting scallions become a nice, golden brown. Cook for about 10 to 15 minutes. Transfer scallions to a paper towel-lined plate and reserve. They will seem limp while cooking, but as they rest on the paper toweling, they will crisp up.
Meanwhile, cook the noodles according to package directions. (If your noodles aren’t going to be ready in the 2 minutes it takes to finish the oil, just turn off the heat under the oil pan until 2 or so minutes before the noodles are done.)
With the oil pan on low, add both soy sauces and sugar to the oil, stirring to combine. Cook for 2 minutes, stirring frequently. It will bubble up, and that is fine.
Drain noodles and rinse under running water. Add noodles to pan, along with some of the scallions. Toss to completely coat noodles with the scallion oil. Taste and adjust with salt, if needed (you probably won’t need to).
Transfer noodles to a serving bowl or individual bowls. Top with remaining scallions. Serve.