Earlier quoted context omitted.
Apparently KaiOS is a fork of Firefox OS/B2G. So... where's the code, yo? I've scoured Github, but no sign of it. edit: nevermind: "KaiOS is based on the Firefox OS open-source project and we are committed to abide by the rules of the applicable open source licenses. Therefore, we’ll make the source code available to the extent required by the applicable open source licenses." So that's a no on giving back to the B2G…
Checking out the site it looks like they are targeting feature phones and they appear to be quite successful at it. Which is funny because Mozilla tried that shortly before abandoning the whole project.
Or maybe the phone partners figured out that they could run the project themselves and when mozilla axed it they just moved on.