I wrote a lengthy post on Seedvault when /e/ was at Android 10 (Q) and the option hidden. I think it’s surfaced now so a lot of the “enable Seedvault” is no longer necessary to know.
The issue with Seedvault before Android 13 (T) is: not everything can be backed up, as Apps are allowed to opt-out of backup - so it’s an incomplete solution. With “fake-d2d” merged in Seedvault (not yet the case), the opt-out is no longer possible and the backup will be way more useful.
For now on all other Androids: it will transfer the apks and reinstall them - but mostly not accompanying app-data and accounts. You’ll see in the app list by its slider which Apps settings can be backed up prior.
/e/ bundles an old Seedvault apk currently, so it’s possible you’ll see bugs that are solved already.
I’ve tried seedvault several times, but only for same device/same android version backup/restores.
There was no prompt that I could see to restore the backup whilst running through the first time set up for eOS. I had to do it after booting using a dialler code for “restore” ie: ##7378673##. Then I could select the usb as a location to restore from.
Here’s some images of what I was able to restore.
I was not able to backup work profile contents although it was possible on Calyx OS
I don’t know if you understood the question. I HAVE e/OS running on an OnePlus 7pro and I am now setting up its successor my OnePlus 9. So I want to copy the complete data, apps and settings from OP7pro to OP9.