re: Grinding holes
I really like my Dremel tool with a long wand attached. Then I use a diamond hollow core bit from https://lascodiamond.com/LascoProducts-CoreDrills.html They have a 2.7mm bit for $8.00 each but they’re worth the money. And of course the bit head and the glass being drilled must be surmerged in cold water to keep the glass from breaking. If the grinding is deep I recommend working the bit in and out a bit to allow the water to cool and letting the bit do all the work (being patient) without putting any pressure on the tool.
Windows listen attentively for the sound of broken glass.