Several years back, @Grande Dog offered some ABN/CBN Dremel bits for chains. I never saw anyone else selling these.A long time ago I tried out a few rotary diamond files on a small 12v dremel style of motor. They cut very slowly and didn't last as long as a regular file. They did produce a sharp tooth, but control was poor. If I did it enough, I'm sure I would have gotten better at it.
I concluded it was mostly a waste of time and money. I think a small carbide mill on the same motor drive would have been excellent, though. Especially on a "rocked" chain.
Philbert