Dual Boot -> Sysadmin approach :)
I am using right now dual boot stock fw / ubport - switching boot from TWRP.
I write down thees steps to my self to remember and for everyone ho would like to try...
Using stock because is good... (dm-verity, rooted , ad-aware .... ) , I could not find any rom with scheduled Power On/Off feature. Needed a solution without wipe. As I understand won't mix the stuff because rootfs.img and system.img is used on ubuntu touch so it will be separated.
So try ubuntu for freedom:
Having already an unlocked Redmi4x, with working StockRom, rooted, dm-verity, and TWRP installed.
Boot to TWRP recovery, Backup ALL stuff including DATA.
Copy TWRP folder outside from the phone , ex. to Your desktop.
Format Data, to remove encryption, otherwise ubport installer won't work.
Copy back the TWRP folder backups to phone and restore stock rom.
Fingerprint and unlock won't work so need these steps in recovery mode:
Mount Data, System, and Delete from '/data/system' folder: files with .key extension and files with 'locksettings' keyword. Reboot to system. Everything should be fine , setup up again a security pattern. Fingerprints works after that.
Reboot to recovery and Backup stock Boot partition.
Backup to fasboot , flash halium-boot.img.
Reboot to Recovery, so ADB recovery is active , flash from Your Desktop:
path/to/halium-install -p ut path/to/rootfs.tar.gz path/to/system.img
Backup Hallium boot partition.
Now You can switch any time , just restore Boot partition. Enjoy .