never heard of nushell, but sounds interesting… but it’s not default anyhwhere yet. I’d go for bash, perl or maybe python? your comments on zfs make a lot of sense, and invalidate my respective thoughts :D

your first two points can be mitigated by using checksums. trivial to name the file after it’s checksum, but ugly. save checksums separately? safe checksums in file metadata (exit)? this can be a bit tricky 🤣 I believe zfs already has the checksum, so the job would be to just compare lists.

restoring is as easy, creation gets more complicated and thus prone to errors