I've got a Pinephone (the UBports CE, though I'm mainly running Mobian right now) Short term, the use cases are as hacker mobile Linux devices with most of the mobile hardware working (device drivers are still a WIP, Linux text/server software works flawlessly, GUI software is hit-or-miss right now) Long term, I'm expecting them to be perfectly serviceable basic mobile handsets. But they are still a ways off from being 'daily driver ready' (i.e. power management isn't in the same league as other mobile devices and quite a bit of flaky/missing functionality) Another area still needing work is that there are only a handful of desktop apps that have been reworked to have a scalable UI for mobile.

Generally things are still sluggish and battery life is not great yet, which is to be expected since no mobile devices really existed out in the wild for raw Linux until very recently. Now that they do exist, things are improving rapidly. For example: a month ago battery life was atrocious. Today it's merely bad (compared to what you're used to on iOS/Android)

So what does this feel like in terms of real world usage?

1) Want to use it to place/receive phone calls/text messages... it will work, to a degree... some/most (depending on distro) of the time.

2) Want to run a web server or open a terminal and ssh over to a server... pretty flawless.

3) Want to run a GUI app designed for or adapted to mobile... the list is growing weekly, if not daily.

4) Want to run a GUI app designed for desktops (i.e. no work has been done to adapt for mobile)... prepare to be disappointed, if you can use it at all.

5) Want to run your favorite iOS app? No.

6) Want to run your favorite Android app? If it's open source, probably will be possible soon-ish. Proprietary apps? Probably not if they rely on proprietary Android/Google services.

I'm using a pinephone, and contrary to most people, it's actually my "daily driver".

This was made possible mainly because I have prepared for about a year for GNU/linux phones (thinking of the librem5 at the time) by replacing all my commonly used apps with similar webapps.

All in all, I don't have an advanced usage of my phone, so it may be what makes it possible to use the pinephone. I don't commute (no need for maps, games, durable battery), I don't often take pictures, my only real need for my phone is the hotspot (because it's my only internet connection) and calls/messaging.

The pinephone is extremely cheap hardware and it can be felt. Opening firefox takes a good 10 seconds, and browsing with it is a pain. Gladly, GNU/linux is very good at running on poor hardware. I just replaced the browser with elinks, which I run through tor, just like on my laptop, and it does the job. Lollypop works well to listen to music while I'm out. Calls and text messages are good enough.

The real cool thing, though, is how hackable it is. After a few months with the phone, I've played a lot around the idea : how to make apps that doesn't use much power? Because, the battery is very bad. And a few months after, my answer has been to build C applications that runs as CGI apps with html static interface rendered by nginx (the idea being to only run the program when I need it rather than constantly as a daemon). This is absurd, this is fun, I love it.

So, as far as I'm concerned, GNU/linux phones are validated. Now I'll want something with better hardware, so I'll wait for the librem5 to see if it delivers, then switch to it if it does.

EDIT: oh, I forgot to mention a step, it must not be clear that way : I made webapps on the phone rather than GTK apps, because that way I can use the apps from my laptop, using the IP address of the phone on the local network.

I am using Sailfish OS on a Sony Xperia XA2. I am using it now for about 1 year. Before that I used Sailfish OS on the original Jolla 1 for 5 years. I have also used a Nokia N9 with Meego Linux, which can be considered a forerunner of Jolla/Sailfish.

It uses Qt, Wayland, Systemd. The original Jolla 1 even used Btrfs, which was deemed a mistake. Sailfish OS is available on more devices, like the Pinephone, Fxtec, Cosmo Communicator and others. If you have the official version for Sony Xperia, you get Alien Dalvik, with which you can run Android apps. I am using Whatsapp and Firefox as Android apps this way. I am still hoping that Signal takes off for mesaging, a native app like Whisperfish is something I would really enjoy. With Whatsapp a native app is not possible, there have been threats for lawsuits.

I am very happy with Sailfish, and have been for 6 years. I enjoy having plain linux on my phone, being able to use ssh as root and having a device that I trust. There are some 'costs' involved, like having less shiny bling and less apps available. Companies like Apple and Google can spend billions on their phone platform. Jolla only has about 100 employees in total. You do have to adjust your expectations somewhat.

Jolla have received criticism about not having open sourced all their software. I do understand that criticism, but that argument doesn't make Apple or Google look any better :) I am curious about where linux phones will go in the next years, but currently Sailfish is good for me.

I have it in addition to my Android phone. I am actually really impressed on how well it works (I use Mobian). Email, maps, calendar, and web browsing all work. The camera sort of but not really works.

The only thing stopping me from using it as a daily driver is MMS:

https://sr.ht/~anteater/mms-stack/

Ubuntu Touch seems to be the closest to be able to have MMS (it uses Ofono,all of the other distros seem to use Modem Manager). However, it is a bit disappointing as no ground seems to be done on it. I admittedly don't have experience in that, but I would be more than willing to donate time/money if I knew how to.

The answers won't be complete without mentioning the Maemo/Meego series of phones, including the Nokia N900 and N9.

The N900 keeps its appeal today because it's fully programmable (even if toolchains are woefully outdated), and the community is still (after 10 years!) vibrant. It's also small, offers a hardware keyboard, has decent battery life, and has the usual gimmicks expected from a smart phone: camera, GPS, GUI package manager, etc.

There are a lot of videos on Youtube, e.g. https://www.youtube.com/watch?v=bH3RbrwhNd8

I've been using my Freerunner for over 10 years. I've tried it with a bunch of distros (including the first version of Android when that came out, which was nice but sluggish); I've generally stuck with QtMoko (although that was last updated in 2014).

The battery struggles to hold much charge any more, so I've been waiting for a replacement which isn't a "freedom downgrade". These newer offerings are exciting, but seem a little too beta for me to switch quite yet.