Hi, I noticed your project and feel that I will have no problems completing it for you. I am experienced with the raspberry pi, and gpio programming for the pi.
I do not have a pi zero on hand as I am working with the rpi 3, so I will be testing with these.
I can have a demo program where the pi reads the nmea protocol off the gpio pins and displays it by Wednesday. And will make any changes you need by Sunday.
Lastly you will see that I am trying to get back into freelancing, this is why I will not request a milestone until you see the work beforehand. Please consider my bid, I will do excellent work for you and have it done on time.
Joel