1. No, you cannot drive to the next city.
The country is big but we have only 57,000 people and 13 towns. You can imagine how far the next city is. Buy a plane ticket or take the Friday ship.
2. We don’t care about McDonalds, 7-Eleven, or Starbucks.
Greenland is still yet been untouched by franchise companies. Go to a regular store with a Greenlandic name and I’m sure they have what you need.