Works like a charm. This is exactly what OP wanted (transferring the whole thing verbatim into a collection of partition images) However (please read on)
Word of advice for anyone reading this: I come from a time where we used things like CyanogenMod, ClockWorkMod and SuperSU. A/B slots didn’t exist and recovery partitions were a thing. Due to my own ignorance on how things work nowadays I shot myself in the foot a few times over the last few days. I lost all my user data once, and at some point I even managed to brick both slots at the same time.
Since it was pretty painful for me, some hints on things to be careful with:
- If you begin tinkering with TWRP, at some point you’ll probably want to unlock your bootloader. Make sure you have a working, full backup first because unlocking your bootloader will wipe your data partition clean (yes I learned this the hard way…)
- read about A/B slots and make sure you understand the basic principles before doing anything at all. When you backup and restore from TWRP you should know which slot you’re backing up or restoring to!
- It’s not really a good idea to install TWRP permanently before you have a working backup to fallback to and a working alternate slot to boot, so you can “adb push” the files from it. TBH I don’t really understand how this works now that there’s no recovery partition, but whatever tricks it’s doing to blend it into boot partition they seem dangerous…
- I recommend reading this thread too from the developer of TWRP/FP3 port, lots of useful info in it.
- If when trying to recover you think of going back to FairphoneOS, keep in mind this procedure will install it to both slots simultaneously. If at that point your data partition was being managed by /e/OS, then both slots will complain about data being corrupt and demand that you perform factory reset
- Edit: I almost forgot. Do not recover every partition! This and this recommends only boot, system, vendor and data. However on some of my attempts this wasn’t enough, so I also included in my restore dtbo, product and vbmeta which are the ones listed in /e/OS install instructions. I’ve restored firmware and EFS at least once and nothing bad happened, but I really don’t recommend it. If I understand correctly what “firmware” means here, I guess this could permanently brick your device. And I’ve read somewhere EFS is where IMEI data is stored so better not play with that, unless you actively want to tamper with GSM settings (is that even legal?).