By activity I mean chat activity in a given post. Right now the ranking algo for "hot" is based on how many people are chatting + decay time function. It's somewhat simplistic for now (still mvp), but I have ideas for other signals that could be used to determine how relevant a particular conversation is. It's certainly vulnerable to being gamed, but I think there are ways we could try to limit that, and filter out noise etc.
One of my goals is to focus as much as possible on the conversation and build features around that. For instance instead of a "like" button, it could require a user to _write_ something relevant (just idea). I think the key is that we try new things, hopefully learn from ideas that have been tried elsewhere, and build a place for high-quality realtime conversations.
The site does follow the twitter/IG/twitch model where it's a flat user(nest) hierarchy, but I have considered later enhancing it to allow multiple users to manage a single nest which would allow both community-led or single-entity led. Right now the goal is just to get mvp features and start getting feedback! So thank you :)