The community contributes to PostGraphile development in many ways.
One of the common ways of contributing is to write a plugin, see Community Plugins for a list of some of the plugins that have been made open source by the community.
Community members also help each other on our Discord chat or through example code/projects/tutorials/blog posts. Here are links to some of these (use the "Suggest improvements to this page" link above to suggest more!):
And of course, we couldn't keep progressing this project like we do if it wasn't for the financial support of many community members.