Here’s the video that I shot of my own problematic engine…

https://youtube.com/shorts/M6KD0bGfgbM

I had that noise some years ago on a BMW Alpiner engine. It dropped a valvehead into the engine. Cost me another engine. Could not get the correct head, so had to rebuild another engine. It sounds like it has spun a crankshaft shell and run the crank bearing. The piston is kissing a valve, perhaps.

I would be looking to remove the serpentine belt, to briefly run the engine to prove its not anything to do with ancillaries first. but guessing by the shroud, that has already been done. but would set mind at rest. then with the fan not spinning, you have a chance to get a listening pipe into all the crevices, and especially around the exhaust manifold gaskets. so with a rubber hose, and small funnel over your ear, go around the engine, trying to find the loudest point. -crankshaft damper delaminating?

Having very similar symptoms - same noise but no warning lights or fault codes.

@MikeEdwards - have you got any further with diagnosis or fix?

Nope. I ended up selling it as it was.