Fun books like Boom Chicka boom. Also just ask him things like “what’s that?” At street signs and never tell hum the answer and make him slowly realize there’s a code out there to solve. Also relax. And if you can’t, fyi I found this book to be truly great:
Teach Your Child to Read in 100 Easy Lessons: Revised and Updated Second Edition
https://a.co/d/3HbogNw