This is hilariously possible and still supported to this day in macOS:

A second generation iPod plugged in to my 14" 2021 Macbook Pro
The adapter disaster that made it happen.
The iPod shows up in Finder for syncing music!

All it took was the following adapters and cables that no sane person should own (that I still have lying around):

  • Thunderbolt 3 to Thunderbolt 2 adapter
  • Thunderbolt 2 to Firewire 800 adapter
  • Firewire 800 to Firewire 400 cable