At $WORK we’ve been using the Zalando Postgres kubernetes operator to great success: https://github.com/zalando/postgres-operator

As someone who has operated Postgres clusters for over a decade before k8s was even a thing, I fully recommend just using a Postgres operator like this one and moving on. The out of box config is sane, it’s easy to override things, and failover/etc has been working flawlessly for years. It’s just the right line between total DIY and the simplicity of having a hosted solution. Postgres is solved, next problem.