For an actual NAS solution, meaning your primary goal is storage, then Rockstor, OpenMediaVault, and TrueNAS are the big open source ones I know of. I believe they can all do ZFS and RAID these days
If you’re looking for a system to host self hosted apps, that can also do ZFS storage, check out Incus Containers on a playing Ubuntu or Debian install, and use LXConsole for the UI side.