@mendelsp I haven't had any luck locating a guide for replacing the lightning port, but from looking around it may be doable with a moderate amount of soldering skills. Really, once you have the motherboard out of the case, you have full access to the port and could then proceed to unsolder the old port and solder in a replacement. They seem to be pretty easy to find; here's one that came up on my cursory search; you can undoubtedly find that part in other places like Amazon, eBay and AliExpress.
Replacement for iPod Nano 7th Gen USB Charging Connector Black
As I mentioned, the only guide you really need is the Logic Board Assembly Replacement guide here on iFixit.
iPod Nano 7th Generation Logic Board Assembly Replacement - iFixit Repair Guide
After that it's going to take a little common sense and maybe some ingenuity to replace that port. I'd start with the grounding tab; use either a solder vacuum or solder wick to clean out the solder from that first.
After that you'll need to unsolder the 10 pins and at that point the connector should come off.
Of course, you'd probably have a lot of grateful admirers if you took pictures along the way and made your own guide for that job. You can start with the logic board guide as the basis then all you have to do is document the actual soldering.
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