I would absolutely buy a stripped lower and a 10 pack of 30rd mags per grandchild you have or hope to have in the future. That package can be had now for a $60 lower, and $100 for a 10 pack of mags. There's a pretty good chance by the time the child is old enough to be able to use them all that stuff won't be so easy to come by. The way things are heading you may be handing the kid the best shot they've got at a fighting chance for freedom.
Then, buy the kid(s) some kind of 22 or bb gun they can learn on.
Then, buy the kid(s) some kind of 22 or bb gun they can learn on.