Strange technical writing in this review, and a misleading headline. The phone has a 35mm equivalent focal length lens, it doesn't have a "35mm" full-frame sensor.
A 35mm primary lens is unusual for phone cameras, as usually the primary lens is a wide-angle lens, but 35mm is still quite wide. It isn't very different from the iPhone's focal length eqv of 26mm.
In terms of using it as a zoom lens, typically portraits are taken with 50mm lenses, and the iPhone's "telephoto" lens is 77mm, so 35mm isn't very narrow, either.
Also, Nubia seems to be a brand from ZTE. It sounds like a Nokia ripoff, and aren't ZTE banned in the US? Is this phone the result of the CCP dodging trade restrictions? That seems more interesting than a slightly narrower camera lens.
While photographers use a variety of focal lengths for portraits, the focal length that's most associated with portrait photography is 85mm. This article from lens review site Imaging Resource illustrates the point; most of the lenses are 85mm or equivalent (e.g. 42.5mm on m43 with a crop factor of 2 making the field of view equivalent to 85mm).
I don’t think ZTE are banned in the U.S. I’ve bought and sold them on eBay. I haven’t used one but I think the carriers attached were ordinary American cellular companies.