For the sake of testing I’ve moved from GRUB to systemd-boot with acpi_override for BIOS 0.23, now I have those magic lines:
[ 0.017282] ACPI: DSDT ACPI table found in initrd [kernel/firmware/acpi/dsdt.aml][0x28dc3]
[ 0.017343] ACPI: Table Upgrade: override [DSDT-ALASKA- A M I ]
But there’s no Goodix Touchscreen device at all and system boots only 1 time of 5, it stalls after “SHA256 validated” message 
After booting Windows and then booting to Linux it boots 100%. But kworker/0:2-kacpi_notify process does 100% load on 1 core and still no touchscreen. Hence I suspect that version for BIOS 0.23 is not actually working.
In any case this is a huge red flag for me as touchscreen is essential for a device like P2 Max as touchpad here is very small and inconvenient.
I’m thinking we should officially request GPD company to fix this problem for us as they’ve also stated support for Linux (GPD P2 Max: The world's smallest Ultrabook | Indiegogo update at Jul 31, 2019 • 10:31AM) so its time to provide some 
Also it’ll be interesting how will they fix it in Ubuntu MATE that’s announced for October.
P. S. There should be absolutely no custom kernels as solution to this problem. Those dark times passed years ago and I don’t want to manually update kernels.