Wanted: Unix zip command-line program with zip64 support
Solution 1:
Last time I checked Info-zip was available for just about every OS ever invented and it does do zip64. You may have to build it yourself for your particular system. You don't say which Unix you've got but there is a high chance they are pre-build packages available for yours already.
Just check out the home-page
Solution 2:
Debian (and every other major Linux distribution) package info-zip , which supports zip64, as zip/unzip, so that should be easier to get nowadays. They also fix security issues unfixed in upstream.
https://packages.debian.org/buster/unzip