ZFS Tunings for PostgreSQL
You should always use ashift=12 today unless you have an overwhelmingly good reason not to.

relatime=off might save you a vanishingly small amount. Don't expect it to be measurable.

xattr=sa is important if you use extended attributes (e.g. SELinux) and you have a lot of tables and file opening/closing operations.

logbias=throughput should reduce your disk I/O volume, and it will help with SSD storage where there is no huge disconnect between bandwidth and latency like there is on spinning media.

recordsize=8k will ensure you don't have any RMW overheads. You'll have to decide whether the extra compression ratio achievable with larger recordsize is a net victory in your use case.

You may find the slides from a lecture I gave on the subject useful.