I get the impression that publishing the work in progress online can be a good way to market the book, eg https://www.cl.cam.ac.uk/~rja14/book.html https://www.

I get the impression that publishing the work in progress online can be a good way to market the book, eg https://www.cl.cam.ac.uk/~rja14/book.html https://www.cl.cam.ac.uk/~rja14/book.html Some publishers allow early-access readers to help with reporting mistakes https://nostarch.com/early-access-program https://nostarch.com/early-access-program