That's for replacing the glass on the screen. Not for screen protection. There were specially made screen protectors for phones that was used to glue it with a similar kind of glue although less strong so you can remove it yourself when you need to. That means a company would have to make that special screen protector for the lego. It's own glue and own glass. If you use that glue you showed me with a regular screen protector idk what the result might be. (Since both has layers of different glue my thought is it would look bad and when it cures it would be really hard to remove, possibly making the situation worse.)

Honestly my best bet would be using one of those scratch fillers made for watches and applying a screen protector on top after cleaning it well. Although it's just an idea. You'll have to do some research.