Quad Lock does make a stick on Universal Mount that you can put on more or less any phone case as long as the back is flat. We did this with my wife's iPhone becasue she didn't want the all black Quad Lock case. It seems to be stuck on quite firmly, though this can vary with the case material. Quad Lock lists the plastic types that it does and doesn't stick to. It low profile, but likely interferes with wireless charging. My wife's phone doesn't have wireless charging, so I have no experience with that.
https://www.quadlockcase.com/collect...iant=209699139