Heat the oven to 375°F/190°C.
On a rimmed sheet pan, toss the potatoes and zucchini with the olive oil, garlic powder, salt and pepper. Spread in an even layer and roast until the potatoes are fork-tender and lightly browned, 25 to 30 minutes.
Season the salmon with salt and pepper. Spread the pesto evenly over the top. In a small bowl, combine the panko, Parmesan, lemon zest and parsley. Press the mixture onto the pesto.
Remove the pan from the oven and increase the heat to 400°F/200°C. Turn the vegetables and clear space in the center. Place the salmon on the pan and lightly brush the top with olive oil.
Roast until the salmon flakes easily and the crust is golden, 12 to 15 minutes, depending on thickness. Broil for 1 to 2 minutes, if needed, to deepen the color.
Drizzle with lemon juice and serve immediately.