Today 10 years ago I went to Poland to buy a Phone with pre installed #Firefox OS on. The Phone was a Alcatel One, so very shitty. Two years later I installed Firefox OS on my Nexus 5 instead.
It was a very good concept, but sadly rolled out on too shitty hardware so it never caught on.
Fxos was just android + a custom launcher, it was not a huge investment since it was just a launcher in the end. They focused on low prices, a camera to create video reports and a usable mobile browser.
This is incorrect, it was also Linux-based but completely unrelated to Android.
It was android 5 (or maybe 6 with its 2.6 versione) and the launcher was gaia