G.D.
My daughter did great with abcmouse.com at that age. There are a TON of free sight words apps for phones.
Readwritelearn.org and Starfall are free educational websites.
He will get bored with anything-even cell phones. But ABCmouse.com worked great for us and kept her attention while teaching her.
Another thing I did was label stuff in the house with index cards-window, door, lamp, tons of written words. Try and mix it up and not just rely on electronics.