Combine olive oil and 2 tablespoons za'atar in a large bowl; let stand 10 minutes. Add eggplant and zucchini; toss to coat. Sprinkle with 1/4 teaspoon kosher salt. Place eggplant on a grill pan coated with cooking spray over medium-high heat; grill 5 minutes on each side. Place eggplant on a serving platter. Coat pan with cooking spray. Grill zucchini 4 minutes on each side; place on platter. Place halved lemon, cut sides down, on grill pan; grill 2 minutes without moving. Place lemon on platter. Sprinkle vegetables with 1/4 teaspoon salt and 1/2 teaspoon za'atar. Top with parsley and almonds. Squeeze lemon over vegetables.