It makes more sense to have Nico go LB because his attacking qualities as a midfielder become even better as a LB.
In fact, the general rule is you can make players play further back, but not further up.
On Max, he looks good on the ball... for a CB, the second you ask him to play like a midfielder I think you will see him outclassed by actual midfielders.
But I wouldn't mind seeing him maybe progress into a John stones role, where has is still a CB but enters midfield in possession next to an actual DM.