I'd frankly rather just support the author directly.
They wrote a book, I'm happy to pay for it in some manner and Kindle Unlimited honestly seems like the fairest possible solution, I as a reader aren't required to buy in advance, I can try it to see if I enjoy it and if I do the author gets paid per page read.
They wrote a book, I'm happy to pay for it in some manner and Kindle Unlimited honestly seems like the fairest possible solution, I as a reader aren't required to buy in advance, I can try it to see if I enjoy it and if I do the author gets paid per page read.