Hi Brett,
Boy, the websites selling parts seem to be all over the place on this one.
The part that iFixit sells for the 5th gen is part number 821-1673-A. I saw another vendor selling that part number saying it was for both 5th and 6th gen iPods.
One site I found had the 7th gen antenna for sale and the picture of it shows it as part number 821-00218-A.
[link|https://www.componentidigitali.com/en/componenti-digitali-home-page/spare-parts-for-mobile-phones/spare-parts-for-apple/ipod-touch-7a-2019/flat-antenna-wifi-per-ipod-touch-7a-2019.2.39.686.gp.22512.uw|22699 - FLAT ANTENNA WIFI PER IPOD TOUCH 7a 2019 - Compatibile - 821-00218-A|new_window=true]
However, when searching for parts using that number, yet another site that came up showed that part as being for the 6th gen. A seller on AliExpress has that part number being shown in a listing for the 5th gen.
So at this point I don't know what to tell you. Superficially I can't see any physical differences in the two parts, but Apple doesn't just slap a different number on a part for no reason.
Hopefully some of our repair technician contributors can help out here.