Looks like you found good information then! 
Space reporting is borked after raidz expansion because the old data:parity ratio is still used.
Good news: Space is there. Bad news: The only definitive fix is “backup-destroy-restore”.
You’ve already found that zfs and zpool give different indications…
ZFS reports on what’s actually used on disk, taking account of compression.
df -h on the client always sees decompressed data.
No dedup is best for you. But you really should leverage periodic snapshots, for some safety against ransomware and user errors—and then replication, backups, 3-2-1, etc.
Please use formatted text </> when pasting terminal output, for the sake of readability.