Can I add hundreds of pincodes at once in Delivery Restrictions?

Yes. Go to Plugins → Delivery Restrictions and open the Pincodes tab.

1. Copy the pincodes from your sheet.
2. Paste them into Bulk import (comma/space/newline separated). One per line works, and so do commas or spaces.
3. Click Import. A message tells you how many were imported.

Imported pincodes are added as active and use your Default delivery days. To set a different delivery time or city for a pincode, add it one at a time with the Pincode, Delivery days, City and COD fields and click Add pincode.