A workaround for ZFS on proxmox not supporting ISOs or container templates.

There are two main solutions you can use.

The first one is the quickest and it is to go into storage and create a directory. Set the mount point to a directory of your choice and then choose ISO storage and template storage. I would keep disk storage disabled as directory storage is not good for large data

The second option is to create a NFS share and then mount it in proxmox. This has the benefit of syncing templates across hosts but it does take more setup.