Use them as such, why would you give your screen Internet? Attach a Mediacenter of your choice, e.g. Kodi.

Update firmware over USB.

Yes thats pretty much the closest you can get to fully open source today. I have a number of devices I use:

• A Pixel 5 with Graphene because the modern world relies to much on Android Apps, also used as hotspot,
• A Nokia N9 for reading and light browsing, occasional navigation
• A Nokia N900 with Maemo Leste for secure administrative work.

We also have Sailfish devices in the house

In that case hardware wise you are out of options. With the Librem 5 you get the closest. There you only have the CPU Microcode, Wifi and Bluetooth firmware, and the cellular modem & GNSS firmware.

Software wise you have quite a few options, albeit few are usable as daily drivers.

• Android drops out because it requires hardware with proprietary HAL. You would have to rewrite huge parts of the OS so that it runs without them.
• Postmarket OS is your best bet for a somewhat usable experience
• Many open source systems run, but calls are difficult to setup and partly unreliable.
• Pure OS should fit your goal best, Mobian second.

With a Droid 4 and Maemo Leste you can also get quite close but have no camera.

But you can. Its Linux+GNU with a partially open, partially closed source UI. So you can run tracing utilities and other tools even wireshark!) to check that it values your privacy. That statement that it is a fully closed OS from the OP is wrong.

So does Graphene.

Both ship: Firmware, the HAL components (which are way more critical in my eyes as they have low level hardware access and could hide anything from the OS) Example for these are: The Camera Stack, the Audio Stack, under Graphene the Widevine DRM components.

Sailfish can run without these, e.g. on the Pinephone. Graphene OS can’t Graphene additionally comes with an eSIM binary, which is disabled by default Sailfish comes with proprietary UI components, a choice the company made because of their limited manpower as it allowed them to provide features where currently no open source solution exists or existed at the time of implementation) examples are swipe gestures for the keyboard, MS Exchange support, Android App support. That not great, but far from a closed source system where everything is closed source. There exist many patches for UI components because they are partly open source.

The OS ist still Linux, that is true. It is even LInux+GNU which Android is not. It is Linux with closed source components, thats true too.

No, not at all. Just check the things claimed by @pewpew quickly with a search engine or an AI of your choice (Always check the sources it finds!) and you will see that the overwhleming majority is wrong and the rest is blown way out of proportion. See also my answer to his retort below.

It may be a private phone, but you don’t really know whats going on under those proprietary blobs.

Yes thats not good, but also a problem of many common Linux distributions. If you have any linux-firmware-* packages installed on your system, they also contain similar binary blobs for the firmware. E.g. Intel or Qualcom wireless cards. But you can utilize all tools up to strace under Sailfish OS, to see what those drivers are accessing and check that they don’t do anything bad. Under Graphene OS, you can not do this. (But its resonable to trust the very privacy focused developer that they have checked and tested this and isolated them as far as possible on the OS level)

Sailfish OS is the definition of proprietary software. You need to buy a subscription if you even want to install it on third party devices.

Again this is not correct. If what you claim is true, how comes that the OS is available on all these devices?. Sailfish OS is open Source at its core and easily ported to new devices. What you can do is pay for the licensed content on official devices. That enables automatic updates and proprietary software as the MS Exchange support and the Android App Support. Though for the later you can also install Waydroid because, you know, its Linux! Paying Jolla however gives access to a more comfortable solution and support development of the platform.

It’s like Windows

Um… no. Can you port Windows to a new device? No, its source is closed. Does Microsoft support people hacking their OS? No, Jolla has community meetings for that. Do you have full Access udner Windows? No. Does Sailfish send your data to a third party? No. Does Sailfish show you adds? No, Does it force you to use AI? No and so on and so forth.

Please don’t hate on the one European company trying to do things right. Support them in making things better.

Uh even this short stab is quite wrong. Here notes from Jolla itself for Sailfish OS 5.2

• As promised, users can unlock the Jolla Phone bootloader. A corresponding menu item can now be found at the System Settings / Developer tools
• Users can do factory reset from the System Settings
• Users can enter the recovery mode with the volume up key + power key combination
• Flashable images and fastboot will be provided (coming soon)
• The initial version of the Privacy Switch was implemented. The function is end user configurable and to start with, the users can control e.g. Bluetooth, WLAN, Location and AppSupport status with the switch. Further implementations are coming and the framework is available for community contributions.

The base of Sailfish OS is a full blown Linux, way more open than Android (more options for the user, less secure than Graphene, which has that as main goal) you can easily install/compile Linux software on it.

Close source components are used. Parts of the UI (Jolla is open sourcing more and more), libhybris to run closed source Android drivers, Android App Support.

So yes its not as open source as debian, but offers more freedom to modify the OS than Graphene and gives you near full control.