I wish there were a way to broadcast "I am a in " and generate a decentralized forum (i.e. phpbb 15 years ago). Growing up, all online friends lived hundreds of miles away; as an adult, all my friends have wildly different interests. Nowadays Discord is The Answer but it's not nearly as intimate as a good message board. Maybe that's a function of growing up, but I can't help but feel disillusioned that $someone hasn't come up with a good enough solution for my use case (San Diego retro computing/HAM/etc.) that isn't instantly inundated with real-life politics.
My project[1] will have discussion boards in groups at some point. But not exactly "broadcast", it's more like Facebook groups that you join and do things in.