I've always thought of the StackExchange network as kind of a strange beast. In one sense, it is basically a Reddit clone. It has a "front page", it has "karma", it has "subreddits", etc. And yet, it is something else entirely. Through strict moderation and constraining site rules, it has always maintained a separate niche from Reddit, despite being so conceptually similar. I think there is a real possibility that StackExchange network is basically already compliant with the "threadiverse" protocol (ie the Lemmy/Kbin dialect of activitypub), or rather that the data model of their API could be made to be compliant with almost no effort at all. I think it would be really cool to see some of the questions and discussion threads that get created over there appearing over here. Even if it was a one-way connection, the idea of knitting these networks together is fascinating to me. I have no idea if it would make business sense for them, but then again I don't actually know how StackExchange makes most of their money.