Not really, they are all part of "Star Trek", as are your own excellent DTI books. I'm asking about books not about Star Trek but use the universe as a backdrop. For example a detective story on Alpha Centauri, a hospital drama on Federation Earth, a romance on Kronos
That's still
Star Trek, dude. It's just not
Starfleet.
And no, you'll never find a
Trek novel that doesn't feature a single canon character. Even
Vanguard has M'Benga.
The closest thing to what you're describing is
The Case of the Colonist's Corpse which is a Perry Mason-esque murder mystery pastiche starring Samuel T. Cogley.
But if you want a book that doesn't focus on
Starfleet, there's
Rising Sun which is told from Jake Sisko's perspective but is mainly about a motley freighter crew in the Gamma Quadrant. There's also
KRAD's
IKS Gorkon/
Klingon Empire series.
If you want books that don't focus on regular characters from the TV series and movies, try the novel-only series like
Vanguard. I'd say
New Frontier, but that, by design, has a number of TNG guest stars become regulars in that series, Shelby, Lefler, Selar, and so forth.
But you're not really going to find a novel that doesn't feature Starfleet in some way
and also doesn't feature canon characters. That's just the nature of a media tie-in.
If you want to read stuff set in the
Trek universe that doesn't feature canon characters at all, there are people who can point you to some fairly well-written fan fiction (just not in this particular sub-forum), or towards some sims/rpgs that are essentially collaborative writing groups. I've been in several over the years that were set on civilian vessels or colonies and had little to no interaction with Starfleet.