FirefoxOS was a full OS made on web technologies, like Palm/HP/LG's WebOS. That means apps like Contacts or Dialer were JS apps. I believe the other comment about a new FirefoxOS was more about an equivalent to ChromeOS: a simple native UI shell and a browser on laptops.
As a volunteer in an association helping people that have difficulties with new technologies, an OS with just Firefox would really make everything simpler. Just like ChromeOS, you'd only get a browser (more than enough for 95% of non-professional use cases), but without the Google crap (telemetry and the Google account)
I think that's not unlike what ChromeOS is trying to be? With the APIs like WebSerial and WebUSB enabling web apps to do the same things native apps could for years now. (Of course, you can use these in the standalone Chromium, too.)
> an OS with just Firefox would really make everything simpler
It's relatively easy to build a Linux distro that boots straight into Firefox! You can try Cubic, which allows you to create a custom ISO for Debian or Ubuntu with a pretty straightforward GUI wizard. I once used it to create an ISO for an arcade machine.
As a volunteer in an association helping people that have difficulties with new technologies, an OS with just Firefox would really make everything simpler. Just like ChromeOS, you'd only get a browser (more than enough for 95% of non-professional use cases), but without the Google crap (telemetry and the Google account)