[HOWTO] install eOS GSI on a Treble device

Using the example of a MiMax3 mobile phone I want to explain the installation of a GSI. It is important to choose the right version. The Mi Max3 needs an arm64 a-only version. Which version has to be used can be found out with the app treble checker.
This guide does not have to work with every mobile phone. Therefore I do not guarantee that it works and does not break. As always: You should have a Stock Rom and be prepared for a complete reinstallation.
Let’s go:

  1. Download these files and save them to a folder
    a) with root and device encyption -> e-pie-2020xxx-UNOFFICIAL-treble_arm64_aeN.img from here https://ecloud.global/s/GEf5AXcP4wcCnFz
    b) without root and enryption -> system.img from here https://ecloud.global/s/Yk8dp6fQiSMgEL2
    c) vbmeta.img from here -> https://ecloud.global/s/5NAgkPKzmyCsGsB
    d) TWRP from here -> https://ecloud.global/s/7yQA73Xs3ffzQ8D

  2. When everything is downloaded, unpack the system.zip

  3. Boot your phone into fbootloader (volume down + power key)

  4. Start Terminal in the folder with all files

  5. fastboot oem ignore_anti

  6. fastboot flash recovery twrp_v323-4_nitrogen_nijel8-MOD.img

  7. reboot in recovery

  8. FORMAT data … do not delete, but format the data THIS IS IMPORTANT !!

  9. reboot bootloader

  10. fastboot erase system

  11. fastboot flash system system.img
    or fastboot flash system e-pie-2020xxx-UNOFFICIAL-treble_arm64_aeN.img

  12. fastboot --disable-verity --disable-verification flash vbmeta vbmeta.img
    If point 12. running into an error. go ahead with point 13. point 12 is not always needed

  13. fastboot reboot

After what feels like an eternity, eOS should start