You could always try a build swap and have random players for judges, or one massive build off with like a 10 minute limit due to the amount of people that may build.
You could also create a community project and have everyone build on to it only during streams so we could get live feed back from people watching. You could even do something focused around the viewers like a simple Q&A, “Tell us what to build”, or people could request a building tutorial. That could even be a weekly series just to put online along with guides on the various plugins that Ohana uses.