Like another american surname BO, BOA could come from different european immigration in America. -A british immigration (English and Irish) - An Italian immigration - A Spanish and South American immigration - A hungarian immigration.
BOA is still an italian surname of the region of VENICE, especially the province of TREVISO. It could be a feminin form of BO that in local dialect means OX or OXEN, an animal used for transport.
I ignore the meaning of BOA in the other languages.