I've had an NEC PA271A for years and have calibrated it with the Spectaview puck (looks like an i1Display Pro but it is labeled NEC) and Spectraview II software. I just got a 2020 iMac to replace my 2013 Mac Pro (trashcan) but plan to use the NEC monitor for my LR and PS work until it dies (not sure how to tell when that might be). However, I thought it might be interesting to try to calibrate the iMac monitor so I downloaded Displaycal and it seemed to run with the Spectraview puck. The screens appear to be a bit different, the iMac looks a bit more blue, the NEC a bit more yellow but I am inexperienced with Displaycal so will play with it some more. The good news is that I've got the time, the bad news is that I have the time because of the accursed pandemic.