The software from the N9 became what today is SailfishOS (mostly FOSS, but UI closed), and for something fully FOSS, Nemo is also derived from Harmattan, https://nemomobile.net/
True, but Pine64 facilitates the FOSS community in spades when it comes to shipping a hardware profile with mainline support, and ensuring it's trivial for Pinephone users to run alternative operating systems down to the boot loader.
I'm a developer and the N9 was completely opaque, it would have required spending significant time just to even begin figuring out how to replace the OS.