How do I do an Backup and Recovery with eRecovery.
I gave the adb idea a go to address your initial question.
The following restore procedure worked with a Moto G4 Play “harpia” and full disk encryption. It’s not an A/B partitioned device nor does it use file based encryption as current devices do. But I can’t think of a reason why this shouldn’t work with the MTK device too.
(as the FDE key is also hardware derived, very likely this will not work for the userdata partition across the same models if you want to migrate instead of restore.)
Activate adb in /e/ recovery Advanced Menu and use a client
adb shell
ls -l /dev/block/by-name
# note down links
adb pull /dev/block/by-name/system system.img
adb pull /dev/block/by-name/userdata userdata.img
... more partitions
# restore userdata (or system) again
adb push system.img /dev/block/mmcblk0p39
adb push userdata.img /dev/block/mmcblk0p41
Pushing on /dev/block/by-name links will not work and run aground a No space left on device message as soon as the tmpfs size is reached. I needed to address the emmc partitions directly.
(Aside: the adb backup command itself is only useful with apps that allow in their manifest file to be backed up, and too Google planned to deprecate the command for a long time.)