Although it might not look great, the Internet Sacred Text Archive is a great resource for sacred texts across cultures. It boasts a collection of over 1700 books. It’s better for you to explore the archive yourself than for me to try to explain it. Everything is free to download and in the public domain.
The reason for the dated design of the Internet Sacred Text Archive is the death of its founder John Bruno 10 years ago. Because of this, I reached out by email to inquire about purchasing a flash drive, a more convenient and supportive alternative to just downloading the books to my own flash drive. I got no response. There also haven’t been any uploads in the past 10 years, which is unfortunate.