For a more structured thread/channel kind of thing, have a look at Zulip.
Mumble for voice groups.
Book Reader in f-droid. Keeps a nice catalogue for you, too.
The beauty of the fediverse is that you can have it all: mainstream adoption of the network, with as many niche servers as desired.
I like the ddg bangs too but I’m weaning myself off them, instead using keywords in Firefox. It’s really easy: just right-click (ctrl-click on Mac?) on a search field then select “Add keyword for this search”.
Especially since they started removing (censoring…?) bangs for the likes of Sci-Hub and torrent sites, and since I got thinking that perhaps they don’t need to know a history of all my searches on all the websites.