Lost my iPod Nano 7th gen charging cord

If you mean the cable:

Lightning to USB Cable (1 m) - Apple

I would not trust the cheapo 3rd party ones. They tend to fail considerably frequently. And trigger warnings of incompatibility often too.

Good quality 3rd party ones are fine. Try Belkin, or Amazon Basics

Amazon.com: AmazonBasics Apple Certified Lightning to USB Cable - 3 Feet (0.9 Meters) - Black: Cell Phones & Accessories

The charging cord is called a 'lightning' cable. You could buy one from Apple, but they are way too expensive, so I would suggest that you went to your nearest supermarket/tech store, as they sell 3rd party cables very cheaply. In the UK, they can be bought for as little as a pound!