Your child says reading is boring but will absolutely read a whole book about farts. It starts with the silliest superhero ever, moves through gleeful gross-out comedy, and lands in real gross-out science, where snot and maggots turn out to be fascinating. Every step uses disgusting on purpose to sneak in actual reading.
Two things climb together on this trail: the length of the book, and how the gross-out is doing its job. It opens with the most illustration-heavy, giggle-first story going, then a longer gross-out adventure, then a step-up illustrated novel to prove a thick book can be fun. From there it turns the disgusting into a hook for real nonfiction, from cartoon gross-science to a nasty encyclopedia to a National Geographic photo-fact book. A child who'll read anything if it's disgusting enough will follow this the whole way, and end up reading actual science without noticing the switch.