Heat grill to medium. Combine chickpeas, coriander, cumin, and 1 tablespoon oil in a medium cast-iron skillet. Place skillet on grill and cook chickpeas, tossing occasionally, until golden brown and coriander begins to pop, 5 to 6 minutes. Season with salt and pepper. Transfer to a bowl; reserve skillet. Add green beans and remaining tablespoon olive oil to reserved skillet. Season with salt and pepper. Cook, turning once, until charred and barely tender, 3 to 4 minutes. Toss green beans with chickpea mixture and serve with grilled lemons alongside.