All WWW Users : Backup DB with Drush (customized, as User)

Solution:

for dir in /var/www/vhosts/*/httpdocs; do   user=$(stat -c '%U' "$(dirname "$dir")");   sudo -u "$user" bash -c "cd '$dir' && php -c ~/httpdocs/drush.ini ~/httpdocs/vendor/bin/drush.php sql:dump | gzip -c > db-test-$(date +%Y-%m-%d-%H%M).sql.gz"; done

PRETTY.

for dir in /var/www/vhosts/*/httpdocs; do   
  user=$(stat -c '%U' "$(dirname "$dir")");   
  sudo -u "$user" bash -c "cd '$dir' && php -c ~/httpdocs/drush.ini ~/httpdocs/vendor/bin/drush.php sql:dump | gzip -c > db-test-$(date +%Y-%m-%d-%H%M).sql.gz"; 
done

Without Cache, Logs :

for dir in /var/www/vhosts/*/httpdocs; do   
  user=$(stat -c '%U' "$(dirname "$dir")");   
  sudo -u "$user" bash -c "cd '$dir' && php -c ~/httpdocs/drush.ini ~/httpdocs/vendor/bin/drush.php sql:dump --skip-tables-list=watchdog,cache,cache_* | gzip -c > db-test-$(date +%Y-%m-%d-%H%M).sql.gz"; 
done

Sys: Ubuntu, Webserver