Most bar fights involve drunkeness, impractical clothing, sucker punches, bottles/chairs being thrown and multiple people jumping in. So who knows.
If we are talking a straight 1v1 unarmed fight with NHB rules i'd favour Ngannou though. Just because he likes to box against guys that cant box very well, doesnt mean he hasnt trained kicks, takedowns and subs extensively. He'd have to be very careful of Ruizs hand speed though.