Each project (comprising one or more related software repos, issue trackers, and other resources) has a project leader and maintainers. Pretty standard stuff. Project leader may be semi-permanent or may be elected from time-to-time from the maintainers. Maintainers can code review and merge, project leader is ultimately responsible for ensuring timely communications and merges, representing the project to the board, etc.
Outside of projects there are "guilds" (is there some better more easily understood name for this? Maybe it's just a committee.) that are groups that operate on many projects. Eg. the UX guild might be responsible for making recommendations and improving the UX for all projects managed by the co-op. They also have leaders and each may handle their own affairs, elections, decision making, etc. separately from the others.
@sam I like guild; I've also seen [[squad]], [[party]]
@flancian probably still want a word to refer to "any cross project group". Maybe projects and cross project things are all just " teams", I dunno why I differenti
@sam so perhaps you could have a UX guild and a backend squad and it shouldn't matter.