Here are the instructions to install any GSI on 2e. I was able to install and boot Lineage but have not done extensive testing.
Download an ARM64 AB gsi to your computer. It may or may not have Gapps.
- [ Advanced ] Unlock the Bootloader
- Power off your Teracube 2e
- Hold volume up + power until a menu appears on your phone
- Press volume up until the arrow points to recovery mode
- Press volume down to select. You should enter recovery mode in few seconds.
- Press volume down until “Enter fastboot” is highlighted
- Press power to select and enter fastboot
fastboot flash system /PATH/TO/GSI.IMG
fastboot -wto wipe your phone
- Press reboot system now on your device
- You should now boot into your GSI.
If lineage complains about some permissions, then do a simple setup and do a factory reset after that to start from a clean slate.
Update: A user posted steps on how to get the 3.5 mm jack working.
If something fails, you can always go back to factory by using [Advanced] Installing an Android image w/ SP Flash