Never heard of such a thing, and any Qi-capable cable or Qi-capable external battery pack for an iPod Nano — if such a thing even exists — would be more expensive than the 30-pin cable.
The Qi charger published reference diameter is within a millimeter of the width of the Nano 6th, too. With no mounting included. It will be wider than the Nano, factoring in any shell and mounting.
Maybe you 3D print a Nano-sized holster with a Qi charger, a 30-pin at the bottom, and lash together a charger and the necessary cabling yourself:
https://www.pchintl.com/wp-content/uploads/2021/04/PCH-Wireless-Charging-Device.pdf
https://www.amazon.com/DAOKAI-Wireless-Charging-Standard-Receiver/dp/B09WVMWSXJ
IIRC, the Apple chargers back then mostly provided up to one ampere at 5 volts, which means that linked receiver might work, with appropriate soldering.
As a left-field option, might be able to scrounge an old 30-pin iPad keyboard, and re-use that as the basis for a charger mount.
There are far better places for hardware design questions, though.