

object_store does indeed also support WebDAV among a variety of other protocols, Apache Druid or Apache Pinot probably would be better examples. My only experience with WebDAV is with Nextcloud and hasn’t been that great because it has been very slow, probably should look into it sometime.
EDIT: Apparently it supports CAS, and even has a locking mechanism










Assuming reliability is the priority I would suggest going with Tailscale Funnels or a cheap VPS acting as intermediary.
I don’t have a lot of experience with dealing with GCNAT, but perhaps you could look into some solution with UPnP or RFC 6887.