While the European's Galileo positioning system is only expected to be fully deployed by 2020, the first positioning made using already deployed Galileo satellites was made back in 2013. Also, hardware devices supporting Galileo are already commercially available.

However, I am not aware of any Android smartphone supporting Galileo. 

Are there any known, existing or planned, Android devices and android apps supporting Galileo positioning? 

From what I understand, Galileo support might depend on support within the microprocessor itself. So the question regarding android devices supporting Galileo may boil down to a question about which microprocessor series support Galileo...