OK I'm... not sure how much help I can be since I'm more an enthusiast than a network wonk so the actual backend software does depend on what your servers are running. However, as an example of what I have in mind:

https://tilde.wiki/NNTP

Notice only a primary.secondary partitioning, rather than primary.secondary.tertiary as with Usenet. This is largely a result of tilde.club's NNTP service being fairly small scale when compared to, well, Usenet. Also as it's a small scale community there is little real need for moderation and as my memories of Usenet itself is pretty fuzzy (I moved on from the 90's into PHP based forums, then on to Digg, Reddit, Discourse based solutions, etc.) So, sadly, I don't know how involved Moderation would be other than offending messages hitting the exchange server getting ejected so they're not distributed. Though the wiki article mentions that moderated groupings get routed through for review before distribution and I'm unsure on how practical that is. May require a 'be it on your own head' sort of warning/disclaimer for those wanting to use the service.

I'm unsure if I'm barking up the wrong tree on your request for fleshing out since to me I feel you'd probably want more of a rundown on backend. Other than pointing you to differing projects to have hosted NNTP servers I'm... not sure what else to do there.

HOWEVER.

For public facing groupings.

w10.* feels appropriate here. One could remove the w10. prefix, but for me this feels useful for the sake of organization if people are subscribed to a variety of newsgroup servers be it full on Unix, or other hobbiest projects.

So as example

w10.announcements
w10.hosting
w10.templates
w10.smallnet
w10.foodie
w10.sci
w10.comp
w10.gaming

With more or less groups as deemed appropriate, though I would make the suggestion that religion and politics be hard forbidden topics for everyone's mental health and moderator's welfare.

Main thing I'm wanting with this idea is: 'Well, Reddit is just a web-facing discussion group. A lot of people are unhappy with Reddit, and since w10 seems focused on bringing back the web1.0 era? This also will work on a number of older devices that modern workalikes may not properly service.'