Got 25c Schwalbe One’s on my road bike now. They’re fantastic quite frankly! Tubeless version on my Stans Alpha wheels is so quick and grippy, yet I can get away with just 80psi for more comfort too.
28c versions are available, but as with all Schwalbe tubeless road tyres, you’ll have to get your local Schwalbe Dealer to get them in for you as Schwalbe UK don’t want (quite rightly too IMO) the likes of Chain Reaction and Wiggle destroying the prices on them. Also because they’re such a new product, they want bricks and mortar stores selling them to actually fit them too. Unlike with MTB’s you can’t really reliably ghetto a road tubeless setup, so they don’t want people blaming them for “poor quality tyres” when it’s a home brew setup that is to blame.