What are these huge non-magnetic flakes in my oil pan?

Are those... drill shavings? They seem to be aluminum. The smaller chunks are old gasket material.
I was going to do the valve covers but the top end is really nasty from poor maintenance before I got the truck so I figured I should also drop the pan and clean out the pickup and that's when I found these.

Truck runs fine, no glitter in oil, nothing magnetic in there and I keep a magnet on the drain plug bolt and have never found anything on it. As far as I know these have been in there as long as I've owned the truck, I'm not that worried about it but should I be?

 

Sure looks like an aluminum chip to me. Maybe left over from the manufacturing process.

How does the pickup look, nothing stuck in there? Not much you can do about it other than clean it and run it IMO

 

Maybe a reman engine was installed with poor quality of workmanship

 

Hmm, unknown. The thing I would be worried about is how much of that stuff is on the oil pump pickup screen. Not sure if you can snake a borescope camera in and manipulate it between the inside of the oil pan and the pickup.