kamid is a FREE, easy-to-use and portable implementation of a 9p file server daemon for UNIX-like systems with a strong focus on security and correctness.
Found via https://www.cliki.net/tinmop, where a client for this 9p file server is described.
See also the author's blog. e.g. https://www.omarpolo.com/post/joy-of-elisp-sndio.html