Raw GNSS (Global navigation Satellite System) measurements from smartphones and tablets running the Android N (or newer) operating system has been recently made available to developers. The direct access of raw GNSS data from mass-market devices opens up a world of possibilities to research community for development of new applications. In this study, we examine feasibility of using smartphone in-built GNSS sensor as a passive radar for the purpose of remote sensing of a number of geophysical land parameters such as soil moisture. The methodology is based on reception and further extraction of information from GNSS constellations whose signal bounces off the ground. These ground reflections (multipath) can be observed in the carrier-to-noise density ratio (C/N0) data and intrinsically related to the soil moisture since the primary physical property that affects the L-band ground reflections is directly dependent on the amount of water present in the top 5-cm soil. In fact, exploiting multipath navigation signals in bistatic configuration are called GNSS reflectometry (GNSS-R), also called Signal of Opportunity (SoOp) in the Earth Science community. GNSS-R has been previously employed to number of applications under several different measurement configurations by using either geodetic or specifically designed GNSS receivers from tower, airborne, and space. To our knowledge, the possibility of remote sensing of soil moisture using a smartphone internal antenna, paired with in-built GNSS chips, has not been previously conjectured. This study will represent the first published theoretical and experimental demonstrations if GNSS-R via a smart device is indeed possible.