The reason it's so hard is that the TG has to be curved - and unless that's done perfectly on every single protector (it has to be done individually) it's going to craze or crack along the curve if the full width is glued to the screen. So most of them are made with adhesive just on the edges, and the "ugly black border" hides the fact that the edges are either physically distorting or chromatically (color-wise) distorting.
Use a plastic screen protector. Tempered glass is no stronger than Gorilla Glass 5, it won't protect the screen if you drop the phone screen-down onto a tiny, hard (harder than a Mhos value of 9) cinder (like tungsten carbide which, thanks to centuries of burning coal, the world is filled with). But a cheap adhesive plastic protector will protect the screen from scratching until it gets so bad that you toss i8t and replace it. (And it does give some drop resistance to the screen.)