I don't know if there's any other active coturn helm charts out there, but I forked the most stared one that existed before and gave it a bit of a face lift if anyone wants to use it: https://github.com/jessebot/coturn-chart

It has things like the ability to use existing k8s secrets and persistent volumes and allows you to use either sqlite or postgres. I could add mariadb/mysql as well if others have an interest.