Tempered glass is designed to make things stronger and is fairly involved (it is a heating process that leaves things under compression which means any break has to overcome that first before it gets to propagating a crack), especially for non square sizes and even more so if you think you want a hole in it to run a pin through or something (some might even tell you it can't be done, which is fair with most tools out there).
Normal glass for just a sheet can be cut with basic hand tools or probably longer in a computer to set dimensions if playing with a fun cutter, drilling holes requires something more specialist but they sell glass/tile bits in hardware shops (hard to install things in a tiled bathroom or kitchen if you don't have such toys).
But yeah as long as you don't expect to be throwing your computer, hitting it or kicking balls at it then a simple window if it is sitting on a metal edge part should be just fine as normal glass. Break either one and you will be having to clean up broken glass just the same. The edge will likely also be quite sharp so be aware of that one when getting it into the window slot. Your computer would have cooked itself long before you get any kind of differential thermal expansion or thermal shock problems.
Or if you prefer find any glass picture frame around your house. I bet a lot of money it will not be tempered. They don't tend to break unless you drop them, lean on them or throw something at them.
Looking at the picture if you are getting holes drilled in the sheet to use those same holes as it comes with to mount then I would consider making some rubber washers (cut them with a knife if you have to) for both sides to help avoid over tightening and give it a tiny bit of shock resistance. Be careful when taking it off and putting it down somewhere as putting on a table and forgetting a pen or something is there before leaning on it is what I would be on being the thing to break it.
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