I've seen the other posts, one where the engine was replaced because of damage to the cylinder walls, and I definitely have a similar sound. This engine has 260 miles on it, and I noticed the rattling from day one (4 miles on it). The video is from a cold start, 60 degree weather, all at idle (it actually makes a lot of noise). You can hear the sound at the very beginning, around 2:05, and then around 2:25 when I hover the gas pedal around 1100 RPMs. Usually I'd only hear it while driving around the 2000-2500 RPM range but this time it was most prominent around 1100 RPMs. It seemed like the oil was overfilled so I changed it around 150 miles. 5w20 Motorcraft synthetic blend and the motorcraft oil filter, and no oil consumption as far as I can tell. At first I thought it was the new DI injectors making the noise, or at least that's what I told myself to feel better, but I remember having a very similar sound in my 97 (5.0 HO swap from a 95 GT) before I put on the gt40p heads (whenever I'd back off of the throttle you would hear the same rattle sound very briefly). The sound seemed to go away on the 97, after the head swap, but a couple years later it developed a rather nasty rod knock and has been sitting ever since. Considering everyone else seems to have the 2018; me having the issue with a 2019 could either imply it's not a big deal, or Ford really dropped the ball. This car has been babied for the first 100 miles. After the oil change I did a couple of sprints up to about 4-5k RPMs because I wanted to see what it could do, but only after the car was warmed up after 20 minutes of driving.
EDIT: Going to add my newest two videos to the OP that have the knock. There's actually a few sounds. The diesel sounding knock that is steady is one, but there's also a dull thud that isn't steady, is easy to hear from the cabin, and can be heard with a stethoscope held up to the oil pan. The passenger side video also has another metallic sound that may be piston slap.