How do you put videos onto an iPod classic 5th gen without iTunes?

It is not possible to use an iPod without iTunes on a windows pc or a Mac running Mojave or earlier

On a Mac with Catalina or higher, you can mange your ipod via the finder, the finder is indeed, a pre installed feature on all Macs, but only on Catalina and higher you can use it for managing your iPod

You need iTunes or, if you are using a Mac with OS Catalina (10:15) or later, use Finder, which as far as I am aware, come pre-installed on the newer Macs.