This will build the default output for your Sony Xperia XA2.
$ nix-build --argstr device sony-pioneer -A build.default
The device will need to be booted in its bootloader, or
The boot image can be installed using the following command, assuming it was
built using the previous command.
If you have a system image (
system.img) built, you can use
flash it to the device. Note that it might be too big to fit over the
partition. In such case, it can be flashed on the
This will erase everything on the partition. Additionally, the
common backups methods, e.g. TWRP, will not backup the
$ fastboot flash userdata system.img
This device has a quirky way to get to fastboot.
You have to have the device connected to a computer, or else it will not activate fastboot mode.
Fastboot shows nothing on the display
With the phone connected to a computer, hold volume up and somehow cause a reboot (from the system, or by holding power to force reset).
Alternatively, from a powered-off state, hold volume up and connect to your computer.
Finally, you can always trigger a reboot to bootloader via software. From
within Mobile NixOS,
sudo reboot bootloader, or from an Android-based system
adb reboot bootloader or equivalent methods.
Note that the LED will light up blue when in fastboot mode.