Hi Mika,
 full acpidump of the machine is located here
https://gitlab.com/SergK/icn8528/blob/master/DSDT/dsdt.dsl

From Android:

"What does 'ls -l /sys/bus/i2c/devices' show under android?"
1) sysi2cdev  /sys/bus/i2c/devices
https://gitlab.com/SergK/icn8528/blob/master/Androiddata/sysi2cdev

2) sysbusacpidev - /sys/bus/acpi/devices
https://gitlab.com/SergK/icn8528/blob/master/Androiddata/sysbusacpidev

there is no nothing with CHPN0001 as it is under vanilla linux 4.2.2

3) Dmesg  https://gitlab.com/SergK/icn8528/blob/master/Androiddata/andrdmesg
please note - there is also in it focal_tech mention - it strange but
the guys from Chuwi declared every possible variant in sysfs and  only
that is present in tablet revision (my is rev11 with chipone
icn8528.h) is initialized through corresponding linux module.

<6> : input: chipone-ts as /devices/virtual/input/input3

quoted

cat /devices/virtual/input/input3/modalias gives

input:b000v0000p0000e0000-e0,1,3,k8B,9E,D9,ra2F,30,32,35,36,39,m1sfw
- I guess the key is m1sfw which means loaded firmware.

4) /proc/bus/input/devices
https://gitlab.com/SergK/icn8528/blob/master/Androiddata/procbusinputdevices

Kind regards,
                      Serge Kolotylo