Not for PostgreSQL, but for MariaDB we run replicas in FreeBSD jails on a server with lots of ZFS space. The jailed Maria instances just stop every hour (so the DB flushes everything to disk), the host snapshots all of their data volumes, and then starts the jails back up. Within a minute or so they're fully caught up to the primaries again. Gives us months and months of recovery checkpoints.

It's great because it's a completely clean save from a shutdown state, so when we need a scratch copy of a database it only takes as long as cloning whatever snapshot we want (depending on how far back we need to to), then starting a scratch jail that runs from those clone filesystems. When finished, just shutdown scratch and delete the clones, it's like it never happened.

A previous company I was at did this on the primary. It always seemed to work, but no one was really comfortable with it, largely because there wasn't too much ZFS experience at the time and also because the process did not coalesce the database before doing it. I think it's still a valid strategy, but not one I have had time to verify thoroughly.