So the N20 and N20U has bezels which are painted. So my question is if one were to use the phone naked, would the bezels fade or drop or even get damaged by corrosion from sweat?
I highly doubt it.
If you are talking about sweat removing the paint/coating from the frame, that would probably depend on the quality of their method they are currently using. How they paint/coat their phone now may not be the same as when you had your S7E. I use to take an iPhone 6 on my runs and talking 20 miles a week in Florida weather so I'm talking soaked to the bone and phone after each run and finish is just fine.