Yes,there are researchers who worked on teaching reading to primary school pupils. Eg. LETTER WORD RECOGNITION ON LOW READING ACHIEVERS OF PRIMARY SCHOOL PUPILS IN KADUNA STATE , NIGERIA. BY. ABUBAKAR SADIQ RABIU PhD.
I am also interested in this. I have found Rebecca Anne Charboneau Stuvland's Doctoral Thesis: Approaches to English as a foreign language (EFL) reading instruction in Norwegian primary schools (Charboneau, 2016) - but she investigates years 4 and 5. I have also found some articles on Phonics teaching to young EFL learners, so you might try to search for that.