The DxO One is one of the few survivors of the "camera phone" era of a few years ago, with the most notable contenders at the time being Sony's QX10 and QX100 models. DxO's model likely struck a chord because of its more practical direct physical interface and relatively compact, pocketable size.
At the same time, you're getting a large 1-inch, 20.2-megapixel sensor and f/1.8, 32mm equivalent fixed lens that gives you photo quality akin to a nice compact camera like Sony's RX100 V -- better than any small-sensor smartphone can manage. However, if you're okay with pairing your phone wirelessly, you'd be better off spending a bit more on a dedicated camera like one of Sony's previous RX100 III and IV models or Panasonic's Lumix LX10.
Supported mobile phones are the HTC U11, Huawei Mate 9, Huawei P10, LG G6, LG V20, Moto Z, Nexus 5X, Nokia 8, Nubia Z11 mini, Samsung Galaxy A5 2017, Samsung Note 8, Samsung Galaxy S8 and Huawei Honor 9. You can also select "other" and specify your brand of phone, and hope for the best.
As mentioned, the DxO One for Android is on pre-order for $499 including the Outdoor Shell and cable back door, along with the DxO PhotoLab software. It'll be able to do most of what the iOS version can, but some recently announced features like time lapse and Facebook Live streaming will come later.