You can display a map of your store pickup locations using Google Maps, which allows your customer to enter their zip code to find their nearest pickup location.
1. In order to enable the map in your cart page, go to Store Pickup + Delivery and Settings, then Store Pickup
2. Check the box next to Enable Google Maps
3. Enter your Google Maps API key
4. Click Save
5. Here's the result:
You can test this feature yourself at zapietdemo.myshopify.com.