There should be a bottle cage mount on the seat tube, see attached picture. The available pictures seem to all be renders, so maybe they forgot to add it to those pictures...
I'm considering this frame also for a gravel(ish) use, something like a frankenmod mixed bike, on this MTB frame and big 32" wheels, with drop bars and inverted stem with a lot of negative angle, like -35 degrees ou maybe even -45 degrees, even.

That said, I'm waiting for news on the M size frame, an availability date is yet to be announced. Also, I'm not sure if the carbon fork is already available...
BTW, there's already a dedicated topic for this frameset:
https://chinertown.com/index.php/topic,6824.0.html