Currently it seems that aggregator websites focus on media, articles, etc. One approach would be to aggregate high value discussion posts from various platforms.
There is a lot of valuable conversation that is not being exposed external to the social media platform they are being expresses on.
One of the methods by which many accounts get initial traction is by aggregating high value content from other platforms, just in a different package. For example instagram accounts that source from reddit, etc.
Could have some daily / weekly / summary posts for various topics. This could initially be manual and at some point it could be automated. Links to original source will allow our users to go deeper into a conversation if they would like.