because 3 operating systems apple-linux-windows isn't enough! Just like the 3 web browsers webkit-mozilla-chromium isn't enough. Remove the derivatives, and there aren't really that many different freshly updated and fully functional desktop / phone operating systems available, but it's good to see some. Thank you https://www.redox-os.org/

https://serenityos.org/

https://www.openbsd.org/

https://wiki.osdev.org/Projects