Hello,
I would say yes. I did it on a very thin plastered wall, to fix tesa plastic hooks to hang photo frames weighing less than 2 kg. They've been in place for over a year now, but I'd advise you to press the tape firmly against the wall for a perfect grip.
The more tape you put on, the more weight it will support. Apply several strips along the entire length of the mirror. If you want to be able to remove the mirror in the future, remember to leave 1-2 centimetres of tape sticking out at the bottom (or on the sides), leaving the red protection on the 2 sides (then hide them with a piece of tape).(then hide them with a plant or something) so that you can remove the mirror without fear by slowly stretching the tape flush against the wall (a really ingenious system with this tape!).). It's really worth the effort, because without it, you won't be able to remove the mirror without breaking it.
I always have some in stock in the drawer, it's really an excellent product, for me the best you can find.

Hello. Unfortunately not. I tried it myself. A lot of marketing, but it doesn't last...