The zfsprops man page references "crossmnt" and "no_subtree_check" options, which don't appear to exist on FreeBSD. It also references exportfs(8), which appears to be Linux-specific.
The sharenfs section likely needs to be almost entirely different on FreeBSD
basically, setting 'sharenfs=on' adds the mountpoint to /etc/zfs/exports which mountd(8) reads in addition to /etc/exports
any other value is added as the flags in the file. You can use comma rather than space to avoid quoting issues. sharenfs=-maproot=nobody,alldirs,-network,10.1.1.0,-mask,255.255.255.0
I think there is a way to handle this upstream, as I think we include the 'jail' subsection only if compiling for FreeBSD