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.
Jolla can also be purchased and used in very few countries. 4 according to their list. I don't mind paying for an OS and a phone, but their phone support is also only for very expensive Sony Xperia phones. So I can see why it is not feasible for a lot of people
If you mean the OS, it can be purchased in all of European Union plus some other countries. With VPN you can purchase it everywhere. Though I read that the Xperia phones don't have the necessary bands for USA.