Update: Downgraded one of the iPads to iOS 6.1.3 (writing from it now). Will try to host a home server on it since I can now SSH into it.
https://youtu.be/E7MzfNTSk4A?si=DRLFJ-yQ2lOVgL9J
Great insight into the situation from a professional economist, his videos are based on academic research but presented in an approachable manner.
I use an iPhone 5 downgraded to iOS 6 (tethered) as an iPod. I love how I can unplug my headphones from my work Mac, plug directly into the phone (no adapter required!) and it effectively mutes Slack without actually muting it. Syncing with the latest version of iTunes still works, albeit slowly.
I also use an iPad 4 (tethered to iOS 6) as an ebook. iBooks works great and I love the pseudomorphic design.
See also: https://github.com/LukeZGD/Legacy-iOS-Kit