According to indications from two separate YouTube videos, the newly-launched Google Pixel handset is apparently more water resistant and more durable than what is conveyed by Google's meagre IP53 official rating for the handset.
The IP53 rating with which Google has equipped the Pixel handset implies that, technically speaking, the device is not actually meant to withstand even splashes of water. As such, going by the mentioned rating, Google Pixel handset would be best kept away from any source of water, unless it is protectively encased in a waterproof case.