I'm also 5'-9"/175cm and had a small honzo for a while, the steel version which is of different geometry. I sold it after a few months… fit was good, but the wheelbase felt too short, it didn't like to track straight on fast rocky trails DH.
I think the newer geometry looks a lot better- longer TT and shorter ST too. I'd go medium for sure. I like wheelbases between 45-46" based on bikes I have owned… the WB on this medium Honzo is under 45…small is under 44.. thats short!
I'm an average 5'8", fit perfectly comfortable onto the medium Honzo ST. Pondered for a long while beforehand whether to buy a small based on the geometry of my previous bike, but shop and Kona advised me to go into the medium. To my surprise it didn't feel big at all despite the 24+" TT length and 17+" reach even with a 50mm stem (I'm on a 35mm now), the small would have been too compact for me now in hindsight. And jumping back on any older medium bike with my traditional ~23" TT length feels like riding a BMX and uncomfortably cramped.
I'm somewhat skeptical about the carbon Honzo and its even longer front end, but I think it should be fine paired with the 35-40mm stem. I think the short wheelbase is fine given the longer front center, that's where the stability comes from I would think.