Sailfish OS ‑ Command Line Interface & Customisation
MTP (the same protocol Android devices use) will expose the /home/nemo folder to the connecting computer, both to graphical and command line applications. But it hides some files and folders from the connected system. A more powerful way is to connect through a terminal via SSH, as explained here.
The phone will alert you that there's an update. Go to Settings => Sailfish OS Updates. As always, backup first. Download the update and choose to install it. Once again it complains that I don't have enough space on the root filesystem. This time I decide to bite the bullet and expand the root volume.
Sailfish OS ‑ Applications
A.k.a "sailfish-browser". Its settings are not accessed from a pulldown but from the main app menu => Settings => Apps => Browser. There isn't much. Most notably: no (to me) acceptable search engine. But you can install the Search engines manager from OpenRepos.net, which allows you to search, add & remove search engines.
Getting started with Sailfish OS
I was lucky to get a device that already comes with Sailfish OS 3 preinstalled. This is the most recent free version of Sailfish OS; I assume I will be able to upgrade it to Sailfish X (same version + Android support) if I want to. If you need to start from scratch (you will need a Jolla account), instructions are here.
No More Android ‑ Part 2 ‑ Welcome back, Nokia!
Nokia 130 New for 35€. I happened to still have a 2GB MicroSD card lying around, and put it in there. And a SIM card of course. Charging and connection to the computer via USB (not C, but the slightly older - MicroUSB I think). It has a headphone plug, can play MP3s (and MP3s only) and an FM Radio.
Resurrect a Nokia N900 ‑ Tweaking & Customisation
Some suggestions are taken from this and this wiki article. Just a better kernel. I'm not going to overclock. http://wiki.maemo.org/Kernel_Power#Installing_the_Stable_Kernel The article then says shut down the device, and boot it up again. Confirm with uname -r.
Resurrect a Nokia N900 ‑ Applications
After lots of trial & error and testing various apps I can now say: In the end I got cuteNews to work: enable the extras-devel repository and install cutenews. Disable Extras-devel after installation. Also see the previous chapter "Secure Encrypted Connections" - some or all the steps outlined therein might be necessary to get this to work.
Resurrect a Nokia N900
The legendary N900. I was surprised that a sufficient number is still being sold on various auctioning platforms, and they can be had cheaply - definitely under 100€, though mine was quite a bit cheaper, and in really good condition: no scratches, the sliding mechanism and keyboard work perfectly, the battery is still OK.