Ok. A filetype where unpacking requires:
1) a server with upload capacity greater than the export size
2) purchasing software
3) installing more software that “macOS cannot verify that this app is free from malware.” and the referenced sourcecode has 2 followers on github.
4) Building new software to read the format
I don’t see any benefit to the end user over .tar or other ubiquitous archive filetypes. I think “proprietary” is accurate even if technically open source. I would have loved to pay you for the software; just not when led on a snipe hunt first.