Thanks for taking a look! Navigating into them is basically the same as standard Discourse. Topics open just like from a regular topic list. I would personally like Chats to open in full-screen by default from this view, it seems more logical to me, but currently they open based on your last-used state (expanded or pop-up).
I can definitely understand the perspective that categories (sub-categories, specifically here) aren’t the same kind of content and don’t seem to belong with the rest. My thinking was that this acts much like the current “Show subcategory list above topics in this category” option for Categories, which I’ve always liked because I also find subcategories to be less prominent than desirable in many cases. Sorting by activity (optionally) just makes it feel more useful and current, to me.
That said it’s also my intent that this be totally configurable. The idea is that you could compose any number of “views” that include or don’t include types of “content”/structure. Right now it’s based on the current hierarchy, so you have everything that’s inside of a given Category, including topics, subcategories, and chat channels. You’ll be able to enable/disable any of those in a given view. The ability to fully compose views outside of hierarchy concerns might also be interesting, e.g. a view that contains topics, categories/sub-categories, and chats from anywhere in the Discourse instance.
I think all of this is probably more confusing if you’re used to and comfortable with how Discourse organizes things. Many of us are. The challenge with these kinds of experiments in a space like this is they will almost inherently seem weird to the audience here. 
But often those new to a discussion space care less about hierarchy than recency. More importantly, even if they do want to only see content in a given Category, chat channels are essentially invisible within the category right now! To me that seems like a grave usability/discoverability error. I set out to solve that problem and along the way decided to make the system more flexible and inclusive. But the core intent is to promote chat to “first-class content”.
Thanks again for the feedback. I’m curious if any of the above helped make it clearer and/or seem more useful!
I’ll try to post a more complete video demo as work continues on this. It’s a backburner project, but feedback will definitely encourage me to keep going. 