Solo founder here (mom of two, self-taught engineer). I spent 3 months building a reading app that adapts books to different reading levels and languages, and launched this month. Four lessons that cost me the most time: Copyright is country-specific. "Public domain" in one country isn't public domain in another — some go by the author's death year, some by publication year. I had to check my starting catalog title by title. Don't compete on catalog size. Big platforms will al...