I wrote a proposal to tackle this exact problem: mix in many different Discourse activity in a central and social user feed.
You can follow your peers in Mastodon and add your “groups” (Discourse instances that you care about, like one about a game you like, one about your ioio hobby, etc) to be interleaved in your forum.
We can also do the same by making a robust Facebook / Twitter integration, that periodically picks a random topic/post from /top and puts it on social media. This is all possible already, but not easy for non-technical people.