On that note, you don’t need to buy books from Amazon, Google, Apple or Kobo. And no I’m not talking about raising the Jolly Roger.
Project Gutenberg offers public domain books for free to anyone in all the formats. While Overdrive or Libby offers you Books, newspapers magazines, and audiobooks for the low low cost of a free library card. Down side on Libby is wait times for some things. Audiobooks can be worse, upto a month or more for the most popular books.