So now I got myself inside the “Apply update” section of recovery and there adb worked indeed.
So as per step 8 of the installation guidelines I was following on your exellent website Bootloader - DivestOS Mobile
I ran adb sideload copy-partitions-fp4-release.zip
Then I saw a terminal scrolling on the FP4 without obvious error message and it ended by “OK”
Then as per step 9 I ran adb sideload divested-19.1-20220808-dos-FP4.zip
My linux terminal ran to 100% without error
My fairphone terminal showed
Finding update package…
Verifying update package…
Update package verification took 45.3 s (result 0).
Installing update…
E: logical partitions ar mapped. Please reboot recovery before installing an OTA update.
Then I hit the “back” button to get back to recovery and perform a factory reset
A this precise moment my fairphone’s terminal displayed
Install completed with status 1.
Installation aborted.
I performed the factory reset and my FP4 eventually answered “Data wipe complete”
Then I hit the button in recovery to reboot the system now and got a scary answer from my Fairphone written in scary color orange
Version 19.1 (20220808)
Active slot: b
WARNING: Previous installation has failed.
Your device mail failed to boot if you reboot now.
Confirm reboot?
I confirmed and it rebooted into… FPOS !?
Edit
I got again into recovery and apply update and ran adb sideload divested-19.1-20220808-dos-FP4.zip
My linux console ran to 100% and end up showing “Total xfer: 2.00x” and my Fairphone terminal displayed
“Step 1/2
Step 2/2”
Then I performed a factory reset and format data and rebooted the system.
Then it booted into DivestOS
I did another factory reset with data format for testing and could boot again in DivestOS.
Then I tested functionality during my day-to-day activities and found the following functions to be comparable with what I had previously observed with FPOS
Mobile DATA
Send and receive phone call
GPS
Wi-Fi
Wi-Fi thethering
Listening music through bluetooth
Selfie camera for pictures and video recording with sound
Speakers
Touchscreen
Display
Buttons
Torch
USB charge and data transfer
I found the following functions to differ from what I had previously observed under FPOS
Send and receive SMS ------ It looks like I do not receive neither notification nor vibration nor sound alert for SMS and have to manually look for them which does not bother me much since 2FA is almost my only use for them and I do receive notifications and vibrations for WhatsApp and Signal messages
Main camera for pictures and video recording does work normally for my use which is basic; however I did not notice an option to use wide angle camera like on FPOS. Here I show a photo taken with my main camera under DivestOS with default camera application and default settings exept that I selected a 16:9 format instead of 4:3; it has been somewhat compressed in the upload process and originally has a better definition.
Then I got myself in the setting menu and looked for update; there was an update available named divestos-19.1 which looked strange because it was supposed to be the version I had installed however I installed it anyway and rebooted exactly in the same system.
Then I decided to try the backup software SeedVault. It proposed me to backup to nextcloud however I had no server to do it so I chose to back up locally even though the software advised against it because if my phone broke it could do nothing to save itself. In the backup options there was an item “Backup status” which was set to “never” and when I tap on it I see a list of settings and apps which are supposed to be backed up however under each is writtent something like “Waiting for backup” with an orange triangle at their right. So far I would say that SeedVault failed to make a proper backup of my system.
My opinion overall is that I can use this OS which is neat and fits my needs; it is based on android 12 and boasts good privacy compared to others and also hardened security although from what I understand to take security benefit would imply a bootloader relocking which I am currently asking myself whether I should try it or not.