I have F8OOK LineageOs 17.1 official nightly installed . Everything works including quad-hifi and this is what i did.
I was in rooted oreo.
downgraded to stock Nougat kdz(F800K10e_00_0914.kdz) by using LGUP
after going back to stock, make sure to factory reset before booting to system
Root and install TWRP using
Dirtysanta method
reboot into recovery(Now Twrp) and format data to remove encryption.
reboot to recovery and flash supersu or magisk provided in the dirtySanta method.
reboot to system and check for root.
if rooted; download and copy to SDCARD or device ;
Latest Twrp(I used Vs995)
tox86.zip
lineage-15.1-20200506-X86CPU-vs995.zip
lineage-17.1-20200506-X86CPU-vs995.zip
lineage-17.1-20201201-nightly-vs995-signed.zip
selinux-permissive-boot-patcher.zip
Magisk-v20.4.zip (incase you are flashing LOS17) and or
Magisk-v18.0.zip (Incase you are flashing LOS15.1)
Gapps
make sure to open each LOS zip file.
edit the updater-script with notepad++ (located at "lineage-15.1-20200506-X86CPU-vs995.zip\META-INF\com\google\android\updater-script)
assert(getprop("ro.product.device") == "vs995" || getprop("ro.build.product") == "vs995" ||
getprop("ro.product.device") == "us996" || getprop("ro.build.product") == "us996" ||
getprop("ro.product.device") == "elsa" || getprop("ro.build.product") == "elsa" || abort("E3004: This package is for device: vs995,us996,elsa; this device is " + getprop("ro.product.device") + ".")

;
remove the above assert line then save it as zip before flashing it
Lets Start.
Boot into Recovery
install new and latest TWRP
Reboot into recovery
factory reset
flash
tox86.zip
format data(if needed)
advanced wide(system,dalvik,data,cache) you can wipe also internal storage but you'll have to mount to pc to copy over your flash files(if you dont have a SDcard)
go to install
flash
lineage-15.1-20200506-X86CPU-vs995.zip
wipe cache/dalvik
reboot to system.
make sure everything works(i.e Fingerprint, flash, camera)
reboot into recovery
advanced wipe(system,dalvik,data,cache)
clean flash
lineage-17.1-20200506-X86CPU-vs995.zip , wipe dalvik/cache, flash Gapps, Flash
Magisk-v20.4.zip , Flash selinux-permissive-boot-patcher.zip, Reboot into system.
Profit? Let me know how it goes.
if you want to move from unoffical to official build , follow these steps:
Backup data partition using TWRP
Factory reset phone using TWRP (option is under the Wipe menu)
Install
lineage-17.1-20201201-nightly-vs995-signed.zip
Install Magisk 20.4 if you wish
Flash selinux-permissive-boot-patcher.zip,
reboot and wait for about 10 minutes until Welcome screen shows on your phone
Power down the phone, and go back into TWRP using the manual method
Once in TWRP, restore the data partition you had just backed up
reboot and wait for another 10 minutes