Duh....
Never mind : seems that the community is planning a new kernel spin.
With some chance that guy will use the slightly newer kernel, same as Android and the card will work.

Stumbling in the darkness, double tap on the screen, that's it.

(Not everyone uses a dark-themed ambiance ;-D )

...but to my knowledge, all known instance of Sailfish OS use systemd.
There's no Devuan-based Sailfish OS clone, as far as I know.

Or a PCB traces problem ?

- e.g.: not enough power provided on the +V rail that is shared by the SD and SIM2 ?

(the solution would be to try to find a way to feed both electrically, or use some less power-hungry SD + SIM just to test if it works)

- e.g.: shared data lines between SIM and SD. If the chipset sees an SD card, it starts talking in "MMC" over the data lines and the SIM can't speak on the same bus ?

(In the later case, the solution would be even more complicated, like using a dual SIM adapter to connect both SIMs to slot 1, and have the slot2 only used by SD).

For the record, FlashTool - the tools used to flash firmware version, that contains XperiFirm (so you can downgrade to Android 6.0.1 Mashmallow, or upgrade to the latest 34.3.A.0.228 or .38 Android 7.1.1 Mashmallow as required by Sailfish OS X), also contains backupTA.sh - which will be able to recover the DRM keys out of a downgraded Xperia.

Advanced -> Trim Area -> RAW -> backup


Flashing the above TA backup, and flashing a Sony firmware will re-lock the boot loader, remove the screen, re-enable DRM and basically put the phone back in condition as it was purchased.

This should make it sellable or sendable back to warranty.

Post processing cannot bring back data that is lost : yes.

BUT.

Post-processing can cheat a lot to make pictures *appearing* more sharp. ( which is more likely )

Post-processing can process the raw sensor data differently than how the RGB data is obtained (I don't know if Sony's official app uses RGB or Raw data).

And indeed as you mentioned : the Contrast detection autofocus implemented in the Sony official app could simply be better than the implementation used by Sailfish X / or in the camera driver / firmware (depending on how focus is implemented in Sailfish's camera app)

I think Apple started the whole "Phone needs to be thin, and thus use weird contraption for their SIM" trend.

Common, if manufacturers didn't try to make phone so thin you could cut cheese with them, we could still have normally-sized SIMs and 3mm audio jacks, and all the current bells and whistles.

And it's stupid anyway, because nearly all users will stick the phone on a protective hard back-cover anyway (I think I'm one of the rare users that rely on a hard holster instead)

(And for the record, the only novelty in the "it's the excuse why the jack had to go" taptic engine is the linear motor.
High precision vibration control that can imitate diverse textures was already done in the Logitech iFeel series of mice, only their motor wasn't linear).