Madueke can't be used in Saka's position much. I agree. While you have a talent like Saka there is no way for that! I wonder what Arteta thinks about the situation after this signing.
He can be used on the left wing too as long as he manages to cut Martinelli. If they are paying that much for Madueke then Arteta should really be thinking of using him in the starting eleven...
I think you're wrong. I rated Madueke a bit lower than Saka. He's both footed, but much more better when he used his left foot. Having him in Arsenal's squad has the purpose to increase the club's depth.
I remind you when Saka was injury, and none in Arsenal was competent enough to play at his position. It makes Arsenal's attack lacked of consistency. So, it's good having madueke as Saka's backup.