I did a blink.py on the Giga R1 Wifi.   The image above has the micropython conversion from the Arduino ports.   D53 converts to PG7.  

from time import sleep
from machine import Pin
Pin_53 = "PG7"
Red_LED = Pin(Pin_53, Pin.OUT)
Red_LED.off()


for i in range(0, 10):
     Red_LED.on()
     sleep(1)
     Red_LED.off()
     sleep(1)