I'm truly sad this failed. The Ubuntu phone was the first phone I've had that I didn't hate. I loved the idea of the phone, and it was nice to be able to use the same scripts that I use on my laptop on my phone. I'm really sad that Canonical never gave it a good effort.
I'd pay a lot of money for an actual open linux phone, but nobody wants to make one.
There is SailfishOS[1]. It's real Linux. It has proprietary parts (e.g. Android drivers, UI widgets, core apps), but Jolla (the developer SailfishOS developer) has contributed a tonne to Linux on the mobile[2].
I use it as my daily phone, and I've developed apps for it, so feel free to ask me any questions.
SailfishOS should hopefully be available for the Sony Xperia X soon (within a month according to their blog posts).
I am interested in Sailfish, but I expect to be able to buy a phone running an OS on my carrier, and it doesn't sound like that is coming with the Xperia X or anything else anytime soon.
If you have to flash the OS to use it, they've already lost, and I'd argue that was one of Ubuntu Phone's biggest problems too.
Besides the fact that the Neo900 is still not available and might never actually end up available, its specs are way outdated. It might have served users back in 2013 when there was still hope the product will become available quickly, but at this point it’s like trying to resurrect Sharp Zaurus hardware and expecting users to not find it horribly antiquated.
(For comparison, the Jolla 1 phone has equal or better specs to the Neo900, but its users have been clamoring for better hardware for years now.)
The website doesn't make the stat easy to find. It's here http://neo900.org/estimate (spoilers: it's estimated to be 990 EUR before tax, or about $1100)
I'd pay a lot of money for an actual open linux phone, but nobody wants to make one.