Has the engine ever run before the zero oil pressure?
I had a friend that didn’t change oil on the regular and had a very similar issue. I told him to change the oil more often and flush the engine. He was adamant it was his oil pump. He did almost everything changed the oil pressure sender, checked with a manual gauge and cranked with the valve cover off.
He finally took my advice and flushed the engine and went to 15w50 oil, it had oil pressure again.
But this was a car that was running and driven daily… you might not be as fortunate as he was.