[notspanishflu]

Ubuntu Touch is alive thanks to the community [0].

Nokia doesn't need to "build and support an alternative OS just for enthusiasts", they just need to give some support to the Halium project [1].

[0] https://ubports.com/

[1] https://halium.org/

[nextos]

Yes, Maemo was just a Debian-based distro. They introduced a few changes, but it was largely just another Linux distro. And that's why it was so good.

It doesn't require big efforts, just a bit of sanity choosing components and perhaps mainlining drivers.