Almost no oil pressure help

I was gonna ask if the oil shot out of the oil pressure sensor hole with the drill; it should shoot out all over the place. If not, then it is the pump, pickup, filter, or filter adapter; those are the items between the oil in the pan and the pressure sensor port. BTW, IIRC, the plug down in the back of the block are there to route the oil through the filter; if this plug is not there, then the oil goes into the engine with full pump pressure, but just bypasses the filter all the time.

At least you are fortunate to be finding the issue BEFORE the engine seems to have been damaged.