I've been struggling with bootloops and infinite boot animation trying to install this ROM, flashing different TWRPs and kernels, but finally managed to run it.
1. Prepare MicroSD with all the files needed for LOS 15.1 and RECOVERY_RAMDIS.img pulled from any stock ROM's update.zip
2. Run Huawei Recovery and let it install stock EMUI ROM
3. Boot stock ROM, pass the first configuration
4. Restart into bootloader;
fastboot flash recovery_ramdisk twrp-3.4.0.0-v1-hi6250-emui8.img
5. Boot into TWRP;
adb pull /vendor/etc/fstab.hi6250
cut out encryption line from it
adb push fstab.hi6250 /vendor/etc/
6. Boot into bootloader;
fastboot flash recovery_ramdisk RECOVERY_RAMDIS.img
7. Reboot into Huawei's recovery and do factory reset and wipe cache
8. Reboot into fastboot;
fastboot flash recovery_ramdisk twrp-3.4.0.0-v1-hi6250-emui8.img
9. Reboot into TWRP;
install LOS 15.1 .zip and Gapps
10. Reboot to system
I hope that anyone struggling with install will make it following this procedure.
I guess after installing other ROMs before, something stubborn persisted in memory and didn't wanted to let go untill stock EMUI ROM reinstall.
Going to test the ROM now. I find Android 10's too buggy atm. Thank you for your work DarkJoker360.
Edit: One bug I find - headphones not detected. 4-pin PC headset works fine, but 3-pin earphones or 3-pin AUX cable aren't detected. I used "Lesser AudioSwitch" to workaround that issue. Please fix if you could