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.
We had two of these that ended up sitting in my desk at work back around that time. They were sent to us free with hopes we would port our (shitty) android/iOS apps to it. One was a bit newer, but they both just felt shitty compared to the equivalent Nexus or iPhone of the time, so I never bothered trying to use it as a daily driver. I wasn't even on the app dev team, no one else wanted them or cared at all. Was fun as a technical curiosity though.