Hello @julyandavey, welcome. I am Alberto, one of the old timers here, and read your post with interest.
As you write, this stuff is already happening. Building hubs for it is another matter. People who are very busy on the ground building their stuff tend to have little time for engaging with aggregators and hubs, unless there is something very concrete in it for them. Trust me, we know. We have been trying to get people to communicate about their projects, so that we can all be within line of sight of each other. But it's hard: doers agree this would be a cool thing to have, but it's just not worth engaging with, as the activity of blogging, debating, engaging etc. competes with many more activities that they give a higher priority to.
In Edgeryders, all projects are participatory. And in every single one of them we need to address what we call "the what's-in-it-for-me question". Not because people are not altruistic: they are! But because being altruistic is hard work, it can get very demanding and risks burning out on people. So, any aggregation initiative we try is aware of the costs of aggregation to the doers on the ground, and we always give back as much as we can (normally by hiring people for meaningful, paid gigs or involving their organizations as partners in paid gigs).