Sand in the pockets is much worse than coins and keys.
I used to work as machinist, and the tungsten carbide dust from grinding stones in the pocket lining would scratch everything.
Wear & tear and mechanical damage is not covered by the warranty.
Please refer to
Gorilla Glass, is damage-resistant, not damage-proof. It is mostly a catchy name for marketing purposes.
For example, here is one of tests by Corning themselves: https://www.corning.com/gorillaglass/worldwide/en/technology/gorilla-glass-5-test.html so, for breakage, as many as 20% of Gorilla Glass 5 screen will fail this test. On the video they themselves speak about damage-resistant, not damage-proof and scratch-resistant, not scratch-proof.
To make such claims as "Gorilla glass screen it should not get such damage" with or without having in-dept experienced and in-depth knowledge about the issue is naive, and worse, it has the effect that other people are mislead into adopting such a naive belief as well.
All materials on this earth will scratch and break, it is only the question of the severity of the stress. And for a manufacturer, an improvement from 1 units of stress to 1.000001 units of stress can be greatly exiting and worth of a global marketing push.
I have always been using screen protection sheets, they do not disturb me. I would be disturbed, very much so, if I had to have the screen changed because of a nasty scratch, such repair costs like 3/4 of the price of a new phone.
And after the change of a glued screen, the device (any device that has a glued screen) is no longer as reliable as it was before the change. More invasive work will factually result in decrease of the reliability. This is a fact, not an opinion.