None of them seem to have been there. One link is from Rivian, one is a news station that have just reported what they've pulled off the wire, and the other two, Hot Cars and Motortrend, were clearly not there either.
Motortrend: Since you're probably dying to know if the Rivian um, died, on the trail—no, it apparently did not. Rivian reports that the R1S electric SUV entered the trail with about 80 percent charge and finished with under 10 percent, reportedly using about 75 percent of the total 135-kWh battery pack energy. Here's the kicker, though—it was only 12 miles long.
Hot Cars: According to Rivian, the stock R1S and its crew completed the Rubicon trail around 3:30 pm after beginning at 7:45 am on August 9th.