I have found ChatGPT a great tool for that sort of task (I study French).
A typical book meant for students trying to improve their reading skills usually starts from a certain level which is fairly high for me currently.
By using an LLM you can tailor-make a story i.e. define your level (“Give me a short story in French, for someone with very limited vocabulary” or “for a seven-year old”) and then adjust accordingly if it’s too easy/hard, ask to use only grammar you have studied (“only using present tense”), pick a familiar topic (“about a someone who studies Physics in college”) etc.