1998 Ford Ranger: no oil pressure on re-starting a warm engine after being parked for 30 minutes

Engine is 2.5L 4-cyl Ford Lima (aka Pinto) unit (a stroked 2.3L).
It was a beautiful day in the neighborhood, & the truck was running great. Parked in Wally World parking lot and went inside. Picked up a few things and came back to truck in about 30 minutes. Cranked it up and clack, clack, clack! (No clicks, just clacks.) Sounded like horrible tappet noise, like huge lash. Looked at oil pressure gauge: zero oil pressure.
No oil puddles, dipstick showed full. Failure occurred between shutdown, sitting for 30 minutes, and starting back up. What the heck could have happened? (Unfortuitously, no peaking is allowed because pulling the oil pan, is a simple three step process: 1) pull engine, 2) place on suitable stand, 3) remove oil pan.) Any ideas?

From out here on the interwebs with only your description, I’d say the timing belt broke.

Find the access plug to the timing cover, place a wrench on the crank pulley, turn clockwise. Is the timing gear moving? No? Broken timing belt. Since the timing belt runs the oil pump…if it is broken, the pump won’t make any pressure.

Thank you very much for your kind reply!
Thanks for suggesting something I can check with the engine in place. I guess I wasn’t clear enough, though. The engine runs and the OHC is turning, so the belt is OK. The noise, I believe, is that the hydraulic lash adjusters are not pumping up, due to lack of oil pressure.
I have had suggestions that it was that type of sudden failure (like a belt snapping), though, maybe a fatigue crack failure in the oil pump shaft, or ditto in the auxiliary shaft, or that maybe that some obscure internal oil gallery plug blew out (if there are any).
Anyway, thanks for your reply! It’s just like a Mustang guy to try to help out! I’m a Mustang guy, too, but since I am an old fart, mine is a '67.