The first 70K books here might not be a bad start...
https://www.zeugmaweb.net/PG/Gutenberg-all.txt
This has a link to zipped bundles of 1000 books.
Note: all together it is 100GB of books as drm-free epubs.
https://www.zeugmaweb.net/PG/
Yes, but which ones? Seems very heavy on fiction, pretty lean on technology, about right on governance (Declaration of Independence, Constitution, Bill of Rights, etc.) about right on Greek philosophers. No primers, no picture dictionaries.
What to exclude? I note the Communist Manifesto included and Mein Kampf is missing, I’d probably give both a pass.