Should fit with the general open source aesthetic—friendly, fun, playful, colorful. Should be something that a developer would want to wear on a t-shirt.
Given the prevalence of animal (PUG, hadoop, python, mysql, hive, SUSE, Mozilla, go, firefox, linux, PERL) and abstract human (drupal, basho, red hat) logos in Open Source, this may be an area to explore.
Another way is to take inspiration from : egghead.io, react.js, gatsby.js, react-router, firebase, netlify or snipcart.
Should not look too corporate. Should not look like IBM, NetApp, Microsoft, VMWare, etc.
The goal for hardcoders is to appeal to developers, geeks types.