It helps to put a known size object in the picture with the item your talking about so one can figure out the size of the screw.

That screw came out of the pump housing. It was SUPPOSED to be staked in after the install of the screw. Someone did not stake it. The result is it vibrated out and fell in the pan. See attached jpg.

Oil jets can come out and they fall out into the pan thru the opening in the intermediate housing. That's how they would get in the pan. But that screw is the oil pump screw.

I agree with FRED, it appears this is the oil pump drive chain lubrication jet which is installed in the oil pump. This is easily verified by removing the front cover and seeing if that jet is missing.