Need assistance implementing a low-power mode to extend battery life for the ATmega2560

#include <zephyr.h>
#include <device.h>
#include <drivers/gpio.h>
#include <power/power.h>
#include <logging/log.h>

LOG_MODULE_REGISTER(main);

#define WAKEUP_PIN DT_GPIO_PIN(DT_NODELABEL(gpio0), wakeup_pin)

void main(void)
{
    const struct device *gpio_dev = device_get_binding(DT_LABEL(DT_NODELABEL(gpio0)));

    gpio_pin_configure(gpio_dev, WAKEUP_PIN, GPIO_INPUT | GPIO_INT_EDGE_TO_ACTIVE);
    gpio_pin_interrupt_configure(gpio_dev, WAKEUP_PIN, GPIO_INT_EDGE_TO_ACTIVE);

    while (1) {
        k_sleep(K_SECONDS(10));
        sys_pm_force_power_state(SYS_POWER_STATE_DEEP_SLEEP_1);
    }
}