Gun safety training is pretty simple actually. Finger off the trigger. Never point at something you wouldn’t shoot. Consider all weapons loaded.
Follow these simple directions and no one will ever be killed or maimed by the “evil gun”.
You could teach your 7 y.o. these rules. I know, cause I have.
Knowing how to safely handle a firearm is almost as easy as learning how to safely handle a sharp knife.
Marksmanship is an entirely different matter, but one should not be required to be a proficient marksman to own a firearm. It's just a good idea.