Piston pin bad ?

That's not a pin or piston noise,..

I've heard a similar sound a coupla times,, an old engine, not run for many years,, it was a sticking valve slapping shut, and freed itself after using an additive..

Another time was also a valve sticking (new build),, it had 2 noises,, the piston slapping a stuck intake valve,, and the sound of the valve snapping shut.. (It didn't bend the valve)

Perhaps use your bore-scope to check the piston valve reliefs for an interference mark from the valve..

I hope I'm wrong..