I haven't see the mandalorian show yet. Cap has feats where he is struck by energy based weapons, he gets punched in the face by thanos whilst the latter is wearing the infinity gauntlet. He took full on shots from bucky in the winter soldier, who used his metal arm. The two things the mandalorian has is varied weapons. And if his armor is true mandalorian armor it should be nigh on indestructible. Even if the latter part is true captain America has the vibranium shield to deflect laser rounds, and should have the strength with the shield to get a clear knockout on the mandalorian. He stood toe to toe with mcu spiderman, and iron man. So Steve should take the majority.