\*2 videos stitched together

This is a 2017 Genesis G90 Ultimate 5.0L V8. 92k miles

Horrible sounds coming from the engine seemingly from the passenger side. No warning lights on, and a OBD scanner didn’t show any codes.

Long story quite short, I bought this car from an online auction knowing it made some noises but the video didn’t do it justice and it’s much worse than I thought. I did a whole bunch of research hoping to figure out what the noise might be, I saw tons of different thing that I hope it could be; from old oil, or a bad spark plug/ignition coil causing a misfire, to a bad cam follower under the high pressure fuel pump, or lastly to a faulty vacuum pump. (Which after further investigation I came to believe that this car doesn’t have a dedicated vacuum pump anyway) But changing those things didn’t fix anything obviously. So I slowly and carefully drove it to a shop nearby for them to take a look at it. 

They took several days to get a look at it and got back to me saying it needed a new motor which I was fearing was the case. But they never actually told me why and I didn’t think to ask for details. So basically I’m a broke college student so I can’t afford a used or especially a new engine, so I’m planning on getting rid of it but I am so curious to know what is actually causing the noise so any thoughts or idea would be greatly appreciated!

More things of note:   
\- The oil I replaced definitely had metal shaving in it. (which is why I assumed the worst)  
\- The sounds went away while pumping the brakes several times, which led me to vacuum pump.   
\- the sounds start super loud when starting up but fade once rpm’s come back down.   
\- the sounds in general are super inconsistent (see videos) they sometimes come and go. Sometimes once the car is warmed up and idling they might be gone for up to 5-10 seconds. From my understanding, rod knock wouldn’t be so inconsistent but idk anymore.

Feel free to roast me for buying a car sight unseen from Copart thinking it’ll be good to go haha. 

Bad engine noises. Rod knock or something else?