The 29 x 2.8 Coronado offers the best of multiple worlds. You get increased ground clearance, stability, and angular momentum, but in a slightly narrower casing to reduce weight and increase pedaling efficiency. A mild and open center tread works with the slightly more aggressive side knobs to offer traction and efficiency in sandy terrain.
Going tubeless allows you to run lower tire pressures without the added weight of a tube. Lower tire pressure has many benefits, including greater traction, lower rolling resistance over rough surfaces, and decreased risk of a puncture-related flat.
Tubeless-ready rims and tires are parts of a complete system that eliminate the need for tubes by creating an airtight chamber between the rim and tire. Liquid sealant is added to the chamber to fill small punctures and maintain air pressure while you ride.
UST (Universal Standard for Tubeless) is a specific type of tubeless system that dictates the shape of the rim and tire beads. UST rims should be paired with UST-specific tires for best results.