I put a metal plate between the phone and the case or the work Samsung S8 work phone is magnet friendly. So I found the magnet that I put it in the middle between the radio and climate control buttons (see pictures).
Usually, I put it in the landscape way, so the temperature knobs serve as support point. In portait way, it holds in place very well, unless you hit a large pothole hard (never happened yet, just guessing based on magnet uses in the past in another car).
