Half-god or small goddess
A modern American creation likely blending the prefix 'Demi' (meaning half or small) with the popular suffix '-iya'. It carries the connotation of a 'little goddess' or someone with divine qualities.
Less common today
Demiya isn't in the latest US Top 1000. It last peaked at #5,327 in 2011.
US births per 5-year period, 1990βpresent (SSA data).