Thank you for the review NicoD! I received my PBP about two or three months ago. Shortly after I received it, the LCD backlight failed so I booted Armbian Focal from an SD card and backed-up and wiped my eMMC before returning my PBP for repair. (They did have to replace the display.) Armbian and my Pinephone dock (with Ethernet) saved the day, because very few distros have SSH enabled by default. I did not know at the time that, unlike my Pinephone, I could have simply unplugged the eMMC memory before returning it for warranty repair. Duh!
I too prefer the XFCE4 desktop. I find it to be amusing that the Manjaro KDE Fusion that ships with the PBP and Pinephone has the slogan, "Enjoy the Simplicity."
I agree with most of your opinions about the PBP and I have similar opinions and experiences with my PBP. I purchased the NVME adapter and also the PBP dock form the Pine Store and I installed a 1TB WD Blue SN550 SSD--primarily for storage capacity rather than performance. It is unfortunately that, even with a larger USB3-PD power supply, the battery still discharges slowly while in use. However, my NVME/SSD battery runtime is better than I expected, based on other reports. The NVMe, APST (Autonomous Power State Transitions) feature seems to work well on my SN550 so I do not set static power states and I just rely on APST to know what's good for me. When I make power inquiries using the NVME cli tool, it seems to make good decisions. I am booting Manjaro from eMMC but then it mounts /root from the NVME SSD. I have not yet risked soft-bricking my PBP by flashing my SIP to boot directly from the Manjaro boot partition on my NVME SSD, but I left the boot partition on my NVME SSD after installation to try SIP booting someday. I currently boot Armbian from SD card.
The one area where Manjaro is working better than Armbian for me is the touch pad. Unlike you, I am not happy with the touch pad dynamics and feel, in general. Using Manjaro, there are many settings accessible via synclient and, with tweaks, I can live with the touchpad on Manjaro. However, I have not been able to get synclient working on Armbian Focal and the available libinput settings are very limited. Some of them don't appear to function correctly either and I've found it necessary to use props ID numbers rather than the text strings for setting properties with the xinput utility too.
There is more information here, for anyone who is interested in tweaking touchpad settings:
https://linuxhint.com/change_mouse_touchpad_settings_xinput_linux/ (Without UBlock Origin, the ads will drive you nuts on this site! :().
My current settings (and the list of very limited settings available on Armbian Focal):
sudo xinput list-props 11
Device 'HAILUCK CO.,LTD USB KEYBOARD Touchpad':
Device Enabled (129): 1
Coordinate Transformation Matrix (130): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000
libinput Tapping Enabled (282): 0
libinput Tapping Enabled Default (283): 0
libinput Tapping Drag Enabled (284): 1
libinput Tapping Drag Enabled Default (285): 1
libinput Tapping Drag Lock Enabled (286): 0
libinput Tapping Drag Lock Enabled Default (287): 0
libinput Tapping Button Mapping Enabled (288): 1, 0
libinput Tapping Button Mapping Default (289): 1, 0
libinput Natural Scrolling Enabled (264): 0
libinput Natural Scrolling Enabled Default (265): 0
libinput Disable While Typing Enabled (290): 1
libinput Disable While Typing Enabled Default (291): 1
libinput Scroll Methods Available (266): 1, 1, 0
libinput Scroll Method Enabled (267): 1, 0, 0
libinput Scroll Method Enabled Default (268): 1, 0, 0
libinput Click Methods Available (292): 1, 1
libinput Click Method Enabled (293): 1, 0
libinput Click Method Enabled Default (294): 1, 0
libinput Middle Emulation Enabled (271): 1
libinput Middle Emulation Enabled Default (272): 0
libinput Accel Speed (273): 0.200000
libinput Accel Speed Default (274): 0.000000
libinput Left Handed Enabled (278): 0
libinput Left Handed Enabled Default (279): 0
libinput Send Events Modes Available (249): 1, 1
libinput Send Events Mode Enabled (250): 0, 0
libinput Send Events Mode Enabled Default (251): 0, 0
Device Node (252): "/dev/input/event4"
Device Product ID (253): 9610, 30
libinput Drag Lock Buttons (280): <no items>
libinput Horizontal Scroll Enabled (281): 1
Tapping Enabled (502): "PRIMARY" (1)