For a long time, I wanted a phone that runs Unix. And I got that, first Android, second Maemo on Nokia N900. With Android I realized that running Linux kernel is not enough. Android is really far away from normal Unix machine, and I'd argue away from anything usable, too. Maemo was slightly closer, and probably could be fixed if it was open-source.
But I realized Linux kernel is not really the most important part. There's more to Unix: compatibility with old apps, small programs where each one does one thing well, data in text formats so you can put them in git. Maemo got some parts right, at least you could run old apps in a useful way; but most important data on the phone (contacts, calendar) were still locked away in sqlite.
And that is something I'd like to change: phone that is ssh-friendly, text-editor-friendly and git-friendly. I call it "Unicsy phone". No, I don't want to do phone `cat addressbook | grep Friend | cut -f 1`... graphical utilities are okay. But console tools still should be there, and file formats should be reasonable.
So there is tui project, and recently postmarketos project appeared. Nokia N900 is mostly supported by mainline kernel (with exceptions of bluetooth and camera, everything works). There's work to be done, but it looks doable.
More is missing in the userspace. Phone parts need work, as expected. What is more surprising... there's emacs org mode, with great calendar capabilities, but I could not find matching application to display data nicely and provide alerts. Situation is even worse for contacts; emacs org can help there, too, but there does not seem to be agreement that this is the way to go. (And again, graphical applications would be nice).