I use Pond Shield/Armor on anything I put in the tank that I’m not sure won’t hurt the fish, but never tried adhering it to the glass. I think
SSteve_C may know this answer. He uses this a lot.
I also read the website and it spoke about fiberglass but not regular glass. But like
TheReefer stated, the surface would have to be sanded down so don't think that Pond Amor would work.
I use it a lot for sealing my 3d background I make. I have never actually put it directly on glass though. As an educated guess though from my many experiences with it..... I would say it would probably stick pretty well to glass, but I couldn't speak of long term durability since glass it so smooth. No to mention cost. Cheapest kit of Pond Armor you can buy is about $75 for a qt & half kit. IMO there would be a lot less expensive ways to do it.