A friend has been running tubeless Schwalbe Big Ones on his gravel bike all year. He gets a kick out of watching the reactions of roadies to his speed on those fat tires.
The Big Ones had shallow file tread and were designed for beach sand racing, little or no puncture shield. But he's had relatively few punctures over a lot of miles, including RAGBRAI. He had one during a casual group ride just after returning from Iowa but only needed a pump to top off the tire. Tubeless worked well for him.
Kinda wish I'd snagged a set of Big Ones from Jenson last fall when they were blowing 'em out for $15 each. But I did snag a pair of Schwalbe One V-Guards for $15/ea this summer from Jenson. Outstanding road tires, but too skinny for gravel.