HP Spectre x360 13-ap0xxxx
Disable Secure Boot: press
Esc to bring up the menu, then
F10 for UEFI,
F9 for Boot options.
You might need to enable Legacy Boot to launch the install media, even on UEFI mode.
Disable the microcode loading if the live environment does not start.
This laptop requires firmware in order for sound to work. See Advanced Linux Sound Architecture#ALSA firmware.
There is still work needed to support the 4 speakers (only 2 are supported).
All the media keys works but the mute button does not light up.
Some configurations include the Intel XMM 7560 4G LTE modem, an updated version of the 7360 with no Linux kernel driver.
Not supported at the moment in libfprint, there seems to be a beginning of work to support those types of fingerprint readers here  The branch synaptics-driver-20190617 contains code that seems to be able to open the fingerprint reader ( if you add the correct device id in drivers/synaptics/synaptics.c ) .
Generates an error after opening though so this is not complete yet.
Keyboard is automatically deactivated when screen is rotated to tent or tablet mode.
Installing iio-sensor-proxy and screenrotator-gitAUR, autorotation works out of the box except for pen input (does not get rotated). Instead of screenrotator-git, you can use this script which auto rotates the touchpad, touch screen, and pen.
Touchscreen Pressure Sensitivity
The touchscreen seems to use the libinput driver by default, with which pressure sensitivity with the included HP Pen does not work. To get pressure sensitivity install xf86-input-evdev and force the use of the evdev driver:
Section "InputClass" Identifier "Touchscreen" MatchDevicePath "/dev/input/event11" Driver "evdev" EndSection
The touchscreen should be at
/dev/input/event11, but to make sure you can use a utility like evtest and verify the location of your touchscreen by testing the input events.
Works with Howdy configured to use
/dev/video2 and the patch referenced in https://github.com/boltgolt/howdy/issues/70#issuecomment-439123621