Restore Nextcloud Backup to different location


i´m trying to move my nextcloudpi instance over from a RPi2 to a docker based x86 deployment.
What would help me is to specify a new target directory via ncpweb as i had my data in /media/USBDrive/ and now datadir is /data/app/data.

I want to avoid mounting a volume to /media/USBDrive

if the data is already there, you will have to edit /var/www/nextcloud/config/config.php to point to the new location