1. You need to go in boot-loader mode: VOL DOWN and POWER - preferable from power off state and when logo appear release buttons.
2. unlock boot-loader (every time is needed if you want to modify recovery or anything else)
3. install original international recovery:
http://www.mediafire.com/file/s3dyqlhsytsflpd/recovery-114.img/file
4. restart in RECOVERY...now you see original recovery : choose English and go and wipe USER DATA (!!!!!!IT WILL ERASE EVERYTHING, ANY IMG< MP# < EVERYTHING FROM INTERNAL MEMORY and DECRYPT IT !!!!!),
erase also cache!!!!!
5. Power OFF
6. Unlock boot-loader (yes, again!)
7. install TWRP 3.3.1 :
http://www.mediafire.com/file/nsu9nr0pdknruxw/recovery-331.img/file
8. Boot into TWRP Recovery
9. now install "Disable_Dm-Verity_ForceEncrypt_02.04.2019.zip" :
http://www.mediafire.com/file/hquo5qjoi45hy9c/Disable_Dm-Verity_ForceEncrypt_02.04.2019.zip/file
In this way you will decrypt your phone and prevent to encrypt it again on reboot. If you don't Disable verity and force encrypt phone will re-encrypt itself on reboot because Vendor partition contain settings to encrypt data. There is a chance that after step 8 you will need to reinstall original international ROM ver. 114 and immediately after that the "Disable_Dm-Verity_ForceEncrypt_02.04.2019.zip"
After reboot successfully (and no encrypting data) go back to TWRP and flash the last magisk.
....If you want to try something else: Download the Resurrection Remix 8. 1, version 64 bit A only gapps from here:
https://forum.xda-developers.com/pr...opment/resurrection-remix-phh-treble-t3767688
This one I found that is working also gapss.
You can find also other ROM (as system image!) here:
https://github.com/phhusson/treble_experimentations/wiki/Generic-System-Image-(GSI)-list ,
or here:
https://forum.xda-developers.com/project-treble/trebleenabled-device-development
About treble experimentation here:
https://github.com/phhusson/treble_experimentations/wiki/Frequently-asked-questions-(FAQ)
For example I like the DESCENDANT 3.1.1 :
https://forum.xda-developers.com/pr...escendant-android-pie-custom-rom-ver-t3840578 but I can not make working gapps on it....till now at least
So, I think i have opened you appetite!
have fun!