Then we have deduplication with floating block sizes, like the restic backup repository format uses. There again though I am not aware of any easy to use wrapper that would be able to apply a similar deduplication method to “dynamic” filesystems.
I remember though, that recently (Q4’22/Q1’23) a software got announced, that can do some partial NAR deduplication,
I assume, you are talking about this ?
It does content-defined chunking and deduplication on the uncompressed NARs using fastcdc.