Jcarnes,
Pretty sure the aftermarket is frantically trying to develop and release parts for the new Titan. I know we are. However Nissan has been EXTREMELY tight about access to the truck for CAD/CAM data, measuring, trial fitments, etc. Plus, even with US-made accessories, there will probably be offshore-manufactured components (for us, it's any molded plastic parts.) For example, if a special molded part must be made, the company has to CAD/CAM design the new piece, 3D-print a prototype, and test fit it (we JUST got access to the trucks, remember.) If all is good, we then must have the mold made and the parts shipped. BEST CASE, this takes 8 weeks. Fortunately, the new XD bed is almost a perfect rectangle (unlike the other big trucks) and is almost the same width and length as the Silverado/Sierra. So, for our company, the new tonneau was extremely easy for to develop (a few different clamps/mounts is all.)
I didn't mean to bore you here. Just wanted to explain why the aftermarket products haven't been flooding the market yet. They will be soon though!
ERIC