I am now of the opinion that you should just download books off indexing sites/IRC/ Usenet/torrents and if you like the book and want to support the author, buy a physical copy, or buy 2 and put one in a neighborhood free library. That maximizes the good you are doing and helps your community instead of just generating Bezos bux.
If you really need it to be secure and private, and are communicating mostly with known acquaintances within a reasonable radius, with low bandwidth requirements, LoRA with encryption is the best bet.
It is a higher bar of entry but at least you can be confident your messages won’t be intercepted in any useful form.