I don't understand how you'd use Davx5 to restore. I only use that app to sync with my Nextcloud, so if I reset my phone I just set it up again and all of my contacts are synced again.
I found something about this. Someone has requested something like this in the GrapheneOS issue tracker.
wario If not, how do i restore from Seedvault after i set up the Phone. I cannot finde a restore Button on Seedbault backup in the Settings.
*#*#7378673#*#* from the dialer app (from Seedvault wiki)