You can run it with much less. I don't recall the bare minimum but with a bit of tweaking 2GB should be plenty[1].

I recall reading some running it on a 512MB system, but that was a while ago so not sure if you can still go that low.

Performance can suffer though, for example low memory will limit the size of the transaction groups. So for decent performance you will want 8GB or more depending on workloads.

[1]: https://openzfs.github.io/openzfs-docs/Project%20and%20Commu...