Found this, so see if it works for you: "Go to the App Store on your [iPod]. Click on your past "purchases", everything you ever installed [iBooks?] will appear here. Install from there and it will ask you if you want the old version."
Afterthought: does the very old iPod even have App Store access??
On a Mac since 1984.
Currently: 24" M1 iMac, M2 Pro Mac mini with 27" BenQ monitor, M2 Macbook Air, MacOS 14.x; iPhones, iPods (yes, still) and iPads.
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