Go for a lever .22lr rifle from Henry ... they have a youth model that is perfect until your son can handle a 13 inch length of pull. My grandson received one at age seven and is still using it at 13. I have a matching one I use and I’m 71! Great little lever gun, and with 60 grain Aquila bullets, a great home defense option.
Thanks - I’ll look into that. We can get rifles here at least.