Heat oven to 350° F. Toss the bread crumbs, lemon zest, 1 tablespoon of the oil, and ¼ teaspoon each salt and pepper on a rimmed baking sheet. Bake, tossing once, until golden, 6 to 8 minutes; let cool.
Meanwhile, cook the linguine according to the package directions, adding the peas during the last minute of cooking. Reserve ½ cup of the cooking water and drain the pasta; reserve the pot.
Meanwhile, heat the remaining tablespoon of oil in a large nonstick skillet over medium-high heat. Season the scallops with ½ teaspoon each salt and pepper and cook until golden brown on one side, 3 to 4 minutes. Turn and cook until opaque throughout, 1 to 2 minutes more.
Wipe out the pasta pot and cook the butter over medium-high heat, stirring constantly, until golden, 3 to 4 minutes. Add the pasta and peas, scallops, tarragon, ½ teaspoon salt, and ¼ cup of the reserved cooking water and toss to coat (add more cooking water as needed to loosen the sauce).
Serve the pasta sprinkled with the toasted bread crumbs.