My ZTE Axon 7 [Android 7] inexplicably wiped its emulated storage area
/storage/emulated/0 while retaining all installed applications, albeit with settings wiped clean. There was also a 256GB sd-card mounted as a add-on, system space. I think it was configured as F2FS and encrypted. I've stopped using it and bought a new phone. I want to image the phone's internal memory and the sd-card, and recover what I can that wasn't backed up. I don't know the best approach, but know there are some hurdles, which I'm unsure how to approach.
What is the best way to image phone memory? Recovery mode and ADB?
Where is the encryption key normally kept? Is it backed up anywhere?
Is there any way to view the contents of a GDrive backup? Any chance it contains key?
How did this happen? Does my story below add up?
Not sure since I was using Android Auto for navigation and music, and the phone was normal. At some point the phone became "weird" with the wrong launcher, which I ascribed to accidentally pressing a wrong button and activating another launcher (I had several installed), and I switched to my wife's phone. Later I realized every app was "weird" and then checked the FS and realized everything, photos, docs, were missing even at the file system level.
Maybe I pushed a system upgrade prompt, or confirmed some other crazy phone action. I was driving and don't know.