My Pixel 9 Pro developed the dreaded green line (while still under warranty), so I had the opportunity to test SeedVault under Android 17. I have ongoing backups to a WebDAV server, but I also copied a local SeedVault copy to my laptop, then I restored stock OS and sent the phone for repair, I got it back yesterday morning, reinstalling GrapheneOS took about 30 minutes. Then I started the SeedVault restore.
TL;DR - it takes almost a day to restore a SeedVault backup and it's almost worthless.
More detailed timeline:
13:00 - Started restoring SeedVault backup from WebDAV, at 15:30 it managed to restore four apps (out of 110), so I aborted and decided to check if the local SeedVault copy will be any faster
15:33 - copying SeedVault to internal storage over USB cable
15:55 - done copying (12 GB, took about 20 minutes)
16:17 - restarted restoring from local SeedVault (the apps restored from WebDAV were already restored)
23:55 - the progress bar is around 45% (48 apps restored, 1 failed)
10:00 next day - still restoring (about 80% done)
11:45 - finished restoring (about 20 hours in total for about 110 apps), tapped "next" and then it went through restoring app data
12:10 - finished, rebooted.
And what did I discover? Launcher settings were not restored (I used the system launcher assuming the system settings backup will restore the home screen icons layout, I previously used Nova Launcher which has its built in backup function and I can store my home screens layout) ringtones not restored, notification sound settings not restored.
This means I will now have to spend half an hour manually setting up icons and widgets on the home screens, customizing ringtones for different SIMs and contacts, redoing custom notification sounds for individual apps. This is not backup, this is a joke.
I also noted Google Play Services and Google Play Store were not restored/reinstalled from SeedVault which may be the cause of some restore failures, so I'm doing another try at restore, now with Google Play Services installed, I will come here in another day or so with more information.