I guess you want to have the sqlite file of pocketbase accessible?
Create a Volume . Maybe /srv/data (create this path on server) and use Filesystem type
Move the app data directory of pocketbase to this volume . https://docs.cloudron.io/apps/#data-directory
Then, mount the same volume in metabase/superset . https://docs.cloudron.io/apps/#mounts . The sqlite will be in /media/<mountpointname>/...
