Maybe try fostering a dog first to see if it works for your family. My HFA son really wanted dog, said he would walk dog, feed dog. I had my doubts so I volunteered to foster a rescue dog. It was a lot more work than I thought! Between training her to go potty on leash (we don't have fenced yard, and walking three times a day, it really put a crimp in my day. I am not a morning person and didn't like going out every am first thing rain or cold or whatever weather. I am sure once a dog is settled things are much easier than doing a foster. But at the end of a week, ,my son said he realized it was more time and work than he was up for. I ended up doing 80% of the work! Also depends if you are working out of home. So we decided to get a pair of cats and my son loves them to death. They sleep in his bed, they hang out in his room during homework.
Just see what works for your family and lifestyle. Wishing you the best in your decision.