The oil pressure may be slightly higher however I think the variable displacement oil pump design may modulate the pressure a bit. With 0W40 in my engine at idle around 35 PSI, while cruising around 1600 RPM about 45 PSI. The problem I feel with the 6.2l is 0W20 may not hold up to higher heat well before it thins out on long highway runs. One the oil starts to warm up over 212F/100C the HTHS starts to drop, then you have a vicious cycle. Once the oil starts to thin, less protection and probably more heat generated.
I personally see nothing good coming from 0W20 a High Torque, lower RPM engine operation propelling 6000+ lbs vehicle.
At a stop light I see 15-20psi and cruising about 45-50.