Sukuna is a Culling Game Player. He was a Player from the exact moment the Culling Game began (when he had 16 Fingers), which is why Yūji, his vessel, was included as well. Arguments like "but he's listed as Itadori Yūji" do not hold water because all incarnated Players use the vessel's name, such as Uraume, Kashimo, Ryu, Sukuna as Megumi, and even Kenjaku as Geto. Sukuna's status as a Player roped in Itadori, not the other way around.
If Ryu has the highest output of all Culling Game Players, then Ryu has greater output than 16F Sukuna.