This is Project Trouble for Android 9.0!
What is Project Trouble?
Project Trouble is a project to simplify the installation of Generic System Images (GSI`s).
It includes a vendor and bootimageto be able to boot a GSI.
Steps to install a GSI:
Download Project Trouble
Download a GSI. (Link:: https://forum.xda-developers.com/project-treble/trebleenabled-device-development)
Reboot to twrp-3.2.3-1-arian (link: https://github.com/xiaomi-msm8998/device_xiaomi_sagit/releases/tag/3.2.3-1-arian)
Wipe all partitions and format data - yes.
Flash a firmware newer then 8.4.19 (link: https://androidfilehost.com/?fid=746010030569970035)
Flash Project Trouble
Select install system-image and select your GSI
[Install GApps]
Reboot