Traditionally, the term referred to vehicles built on passenger car chassis and with the cargo tray integrated with the passenger body (coupé utility vehicles). However, present-day usage of the term “ute” in Australia and New Zealand has expanded to include any vehicle with an open cargo area at the rear, which would be called a pickup truck in other countries.
If you search for “cybertruck ute” you’ll find many publications from Australia and New Zealand calling it that, but I’m talking about the narrower first definition. It’s hard to say whether or not the Cybertruck chassis is a “passenger car” chassis because it is unique, but the cargo tray of the Cybertruck is in fact integrated with the passenger body. (Pickup trucks according to the American definition have a gap in the body between the cabin and the truck bed, and the Cybertruck does not.) You can argue that the Cybertruck is a pickup truck in the American sense since it claims to have a carrying capacity of 2,500 pounds (definitely more than utes generally do, if you trust that number) but it does look like a ute.
The Cybertruck owner’s manual reveals you can carry up to 1,310 pounds in the bed, 441 in the frunk, and 220 in the under-bed storage compartment. The remaining 529 pounds must go in the cab.