Drop in Oil Pressure

Pretty good leak to drop pressure

Perhaps the leak caused the system to gradually run very low on oil.

If the ZERO pressure time was for less than a second at a time, you are probably OK.
One to Five seconds without Oil?  Do you feel lucky?
More than five seconds?  Inspection Time!

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A leak on the suction side (Tank to Pump) will draw air during operation, yielding ZERO pressure intermittently.
It will also leak Oil while parked.

With engine running, the lines going into and out of the oil cooler are under *suction*, not pressure. External evidence of an oil leak there implies a major air leak. At the very least, I'd do the "air in the tappets" test and do an oil system air purge.