That's a point I'm not aware anyone has talked about yet.
Metal polishing compounds, or polishing cloths that are impregnated with a polishing compound.
If they are abrasive enough to, microscopically remove metal.
Which is what you need to do, to remove a scratch in metal.
Then, they must have some fine. VERY fine. VERY hard compounds in there to do the work.
Would Sapphire stand up 100% to such fine abrasive compounds being rubbed against the side of the screen?
It would be quite hard, and take great care to not get any abrasive polishing cream near the screen.