The description sounds like this mirrors a lot of the functionality found in rsnapshot (https://rsnapshot.org/).

What are the advantages here vs. what rsnapshot already provides?

Or backintime (https://github.com/bit-team/backintime).

The only thing I am missing is that it doesn't work for sshfs mounted devices. Which is not provided by any alternative tool which supports snapshots (probably because of problems with hard links, although I never had issues with those over sshfs).

I don't know. I could not find a comparison, but I did find this Reddit thread which gives an overview over different programs:

https://www.reddit.com/r/linux/comments/9tkpxx/rsyncbased_os...

To me, the fact that it doesn't provide a fancy GUI on MacOS is a pro not a con. I'd much prefer to browse the snapshots using a normal file browser.

The Time Machine GUI was cool at first. Now it's just obnoxious.

Also works on Windows via WSL. The repo is active, but urgently needs maintainers.