I’m really not sure. I’ve heard of people using Ceph across datacenters. Presumably that’s with a fast-ish connection, and it’s like joining separate clusters, so you’d likely need local ceph cluster at each site then replicate between datacenters. Probably not what you’re looking for.

I’ve heard good things about Garbage S3 and that it’s usable across the internet on slow-ish connections. But it’s object storage only.