Can you etch glass with the cnc machine and if so what would you use as a cutter
Some folks have used a regular carbide endmill (this has safety implications and is best done with the glass submerged): https://wiki.shapeoko.com/index.php/Materials#Glass
Otherwise, a diamond drag bit is the usual choice:
Get a spring loaded diamond drag bit, available on E-Bay and Amazon. They come with different tip angle that provide etching of slightly different width. The difference may be subtle, I don’t have enough experience to really tell the difference.