They are scratch resistant, just not scratch proof, I am pretty sure "iom-strengthed glass" is just another name for Gorilla Glass
i got my 6 screen covered in Ghost Armor clear screen protector....I love this screen protector, perfect cutouts, perfect size, fits the whole glass display, had a guy at the kiosk did it, no air bubbles at all anywhere, complete clean and clear installation, it is flawless and you cant even tell sometimes that there actually is a screen protector thats how well installed it was(guy at the kiosk did it, put it in a heat box, popped all remaining other air bubbles/pushed them out)
I feel very safe and secure with this Ghost Armor protector lol I know it will hold up great and absorb alot of scratches over time instead of my screen
Honestly , literally there is not much you can do to protect your screen without a screen protector,
a OCD guy like me, where i never keep anything in my pocket with my phone but my phone, where I am always shaking off my pockets to get all lint/sand out before I put my phone in there so nothing can scratch it in my pocket, blowing on my phone sometimes throughout the day to get dust/lint off of it from my pocket, and being very careful where I place my phone (Never in a car cup holder etc) and even doing all this, all my smartphones that I had owned even with care like this, I always still end up finding micro scratches on the screen build up over the months, doesn't affect actual screen display like i dont see rainbow lines or anything like that, but still micro scratches all over the display, it is almost impossible to guard from really with no screen protector you honestly can't do nothing about it and it's not "cheap Apple" , its just not sapphire glass display lol. Your best bet is a screen protector, highly recommend if there is a kiosk by you where they could do the installation for you, that is much better