Actually, there's not been much change from the original fork of FirefoxOS besides the UI changes to be better for non-touch devices.

GerdaOS (LineageOS for KaiOS) allows people to import and run FirefoxOS packages without modification, though many apps will need some changes to allow it to work without a touchscreen.

The unofficial rumour mill says that with the extra investment from Google, KaiOS will probably shift to Chrome(ium) at some point in the future, but that's just a rumour and remains to be seen.