My kids used the Pathway Readers, the Elson Readers, and Treadwell’s Reading-literature Readers from Yesterday’s Classics ( or free online).
The literature is high quality and made of shorter sentences in the early volumes, especially Pathway.
Forgive me if this has been covered, but are you reading aloud, or is he reading the sentence aloud, then narrating? I would suggest the latter. That way he’s getting 3 forms of input: kinesthetic- holding the book; visual- seeing the words; auditory.
Narrating is hard work. Being read aloud to and then narrating would be more difficult for a visual child. Save the read alouds for pure enjoyment for now, is my advice.