jmtr So I have not yet bought mine for my 2013 Prius C, but I was told they only have a fascia for the 9.5" one, just an FYI.
However, I did notice they sell a universal one with metal brackets. If you got those, you might be able to detatch the metal brackets from the OEM head unit (L brackets) and making it work with OEM fascia. I am considering trying this for my prius since I really want the slightly bigger screen.
If you are able to get a bracket to work with the 10.3" or find a fascia definitely let me know.