I am currently building something ESP32-S3 based, after diving into Arduino as a pandemic project. I would pay $99 for an ebook (short, rough) about the entire process - design decisions, hardware prototypes, manufacturing, mobile app, etc. I would pay $199 if it included ability to send you questions with an eventual answer (no real-time response needed). Should mention I'm 99% a software person. Might be a market for this ... Just food for thought.