If the glass is tempered, it is not easily drillable. If it is not tempered, drill away.
Look at the glass with polarized glasses in the sunlight, tempered glass will have dark lines or spotted pattern.
Another way to reveal if it’s tempered is to put your laptop monitor behind the glass and look the monitor through the glass with your polarized glasses. The lines or pattern will be visible if it’s tempered.
That being said, like all free advice, you get what you pay for.