Consider it at least federated? :)

I’ve an account on dbzer0 too and often lurk there as well, however I wasn’t sure about its longevity given the amount of piracy-related activity going on there.

Syncthing?

There is also Borg but I think it doesn’t have the features you’re looking for such as incremental backups and two-way sync etc.

Yep, vectors. See https://github.com/onthegomap/planetiler