I can't tell you which of these are on Oahu (not without spending some time communing with my copy of the FCC database), but a list of ARRL/VEC VEs in Hawaii can be found
here. Also,
this page lists scheduled exam sessions in Hawaii for which notice has been given to the ARRL/VEC. I'm fairly certain that the Oahu Civil Defense ARC sessions are, in fact, held on Oahu.
Also, to clarify some misconceptions: First, you do not need to be an Extra to be a VE, at least not with the ARRL/VEC. Anyone General class or above may be a VE. Also, Advanced class licensees remain Advanced class licensees, with the same privileges as before the sunsetting of the class. A VE who is an Advanced Class licensee may administer Elements 2 (Technician) and 3 (General) but not Element 4 (Extra), as per ยง97.509. For more information on becoming an (ARRL/VEC) VE, see
here.