+1 on the GunVault and other safe storage devices. Of all of my guns, my wife's favorite is the 92FS. I put some Hogue grips on and she absolutely loves it. One of the easiest guns to shoot, accurate and comfortable.
My 7 year old daughter already has a Ruger MKII and a pink Cricket. She can operate both of them. She absolutely loves to be in my gun room with me and helps me reload. I let her touch, hold, handle any of the weapons she wants including the evil AR-15.
She does it under my supervision and we always make sure they are unloaded.
Does she understand what a .45 caliber bullet traveling at 900 fps will do to a person, no, but she understands that guns are both fun and dangerous. The key to what happens is her.
She has gone through Eddie Eagle classes and can recite the 4 principles of EE is she does come across a gun. She knows not to point a gun, even empty, at anything she does not want to kill or shoot.
Does all of that mean she won't pick up a gun out of curiosity and do something stupid? Absolutely not, but my wife and I have done our best to teach her the respect and appreciation of firearms and not to be afraid of them.
I respect any parent's decision to train their child with firearms as they see fit and realize there is no one size fits all answer. This has been our approach.