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.
People talk about FFOS like it was a failed project while in reality it was successfully commercialized and is so popular it has a native WhatsApp client. It has ~70x more users than LineageOS. Maybe Mozilla didn't knew how to make money out of it but it's definitely was a great OS project.
I always thought it'd be more of a feature phone type os. Couldn't compete with what Android had to offer to the mainstream Western market at the time using primarily HTML, but I'm glad to find out that is what it turned into.
KaiOS runs on feature phones, with some advanced stuff like WiFi, 4G net and an app store. It should run on low-end smartphones, but I don't think any have been released yet.
IDK, I still like them. Definitely still managing not be evil. And keep in mind they are competing with multi-billion $ corporations that pretty much control how the web works today. Google (and others of course) first turned the web into ad funded business and then used their huge ad revenue to build a really good browser and promoted it using shady practices. What was Mozilla supposed to do? Sometimes simply having better software is not enough.