There is no 7th Gen. Everyone (including iFixIt, AppleInsider, etc.) needs to stop saying it. This is simply a software update to the 6th Gen nano.
Every product sees variations in its internal hardware over the life of manufacture. This is effected by suppliers, their prices and ability to meet the demand. However, the specs of the device and what it can do remain the same. It is like deciding to put every ready batteries in your flashlight instead of duracell. Same flashlight, just different batteries.
R