Troubleshoot if the iPod is in iTunes or Finder.
Because Apple no longer actively hosts these legacy files on a public-facing storefront, you must source them from archives or direct server links: Reddit·r/IpodClassic ipod classic firmware 2.0 4 download
If you are running an older Mac (pre-Catalina), you might have the utility tucked away in your Utilities folder. This often caches older firmware files locally. Troubleshoot if the iPod is in iTunes or Finder