I’ve a Redmi 7A, building an image is difficult cause Xiaomi doesn’t made open-source system files. The only way for installing /e/ seems to be the GSI, some people succeeded to install Lineage Pie and AOSP 10 by using a GSI without any bugs due to hardware, except VoLTE which has not being tested.
Be careful, there is special Installation instructions for Xiaomi’s devices unlike for other phones due to the boot partition that avoid booting from non-MIUI systems, read the wiki.
What’s working and what isn’t :
Wiki :
https://github.com/phhusson/treble_experimentations/wiki/Xiaomi-Redmi-7A
/e/ GSI :