Does the liquid applied by the coating machine for phone screen actually protect against heavy drops?

The vendor in the mall gave you a highly exaggerated sales pitch regarding the liquid from the coating machine for phone screen. Let us separate the science from the marketing hype. Liquid nano coating is essentially a chemical solution of silicon dioxide. When applied to the screen and cured with UV light it does indeed fill the microscopic pores of the glass creating an incredibly smooth ultra thin layer. This layer provides phenomenal scratch resistance. If you put your phone in your pocket with keys or coins the nano coating will prevent those annoying micro scratches. It also acts as an oleophobic layer repelling oil water and fingerprints making your screen look beautifully naked and glossy.

However to answer your most critical question: No the invisible layer applied by the coating machine for phone screen will NOT protect your phone against a heavy drop on a concrete floor. Tempered glass protectors work by absorbing the kinetic energy of a fall; they shatter so your actual screen does not. Liquid nano coating has zero thickness and therefore zero shock absorption capabilities. If you drop a phone with nano coating face down on a sharp rock the kinetic energy transfers directly into the original screen and it will shatter completely. Nano coating is perfect for people who are highly careful with their phones and just want scratch protection without bulk. If you are clumsy and drop your phone frequently stick to a high quality 9H tempered glass.

I used the nano coating on my Samsung S22 Ultra because normal glass protectors ruined the fingerprint scanner. It kept my screen scratch free for a year but when it fell off my desk the screen shattered instantly. It is not drop proof.

The vendors lie a lot. They will hit the screen with a key to show you it is strong but glass is already highly scratch resistant to metal. They will never drop the phone on the floor to demonstrate its strength because they know it will break.

It is fantastic for the camera lenses! I ask the vendor to apply a drop of the nano liquid over my rear camera lenses. It keeps the camera glass perfectly clear and scratch free without affecting picture quality like plastic protectors do.