Não sei se é possível com a criptografia incluída (suponho que seria), mas normalmente você pode retomar os envios com falha com sinalizadores especiais send -t | recv -s , se o pool oferecer suporte a ele (a documentação é de illumos, I suponha que seja o mesmo com o ZoL):
zfs send [-Penv] -t receive_resume_token
Creates a send stream which resumes an interrupted receive. The
receive_resume_token is the value of this property on the filesystem or
volume that was being received into. See the documentation for zfs
receive -s for more details.
zfs receive [-Fnsuv] [-o origin=snapshot] filesystem|volume|snapshot
zfs receive [-Fnsuv] [-d|-e] [-o origin=snapshot] filesystem
-s If the receive is interrupted, save the partially received state,
rather than deleting it. Interruption may be due to premature
termination of the stream (e.g. due to network failure or failure
of the remote system if the stream is being read over a network
connection), a checksum error in the stream, termination of the zfs
receive process, or unclean shutdown of the system.
The receive can be resumed with a stream generated by zfs send -t
token, where the token is the value of the receive_resume_token
property of the filesystem or volume which is received into.
To use this flag, the storage pool must have the extensible_dataset
feature enabled. See zpool-features(5) for details on ZFS feature
flags.
zfs receive -A filesystem|volume
Abort an interrupted zfs receive -s, deleting its saved partially
received state.
Eu primeiro tentaria localmente (canalizar, sem netcat ou pv ) com um sistema pequeno e apenas Ctrl-C da transferência para ver se funciona em princípio.