> Hetzner volumes are, in my experience, too slow for a production database. While you may in the past have had a good experience running customer-facing databases on AWS EBS, with Hetzner's volumes we were seeing >50ms of IOWAIT with very low IOPS.

There is a surprisingly easy way to address this issue: use (ridiculously cheap) Hetzner metal machines as nodes. The ones with nvme storage offer excellent performance for dbs and often have generous amounts of RAM. I'd go as far as to say you'd be better off to invest in two or more beefy bare metal machines for a master-replica(s) setup rather than run the db on k8s.

If you don't want to be bothered with the setup, you can use one of many modern packages such as Pigsty: https://pigsty.cc/ (not affiliated but a huge fan).