I never understood why one would use MinIO over Ceph for serious (multi-node) use. Sure, it might be easier to setup initially, but Ceph would be more likely to work.

For the single node use-case, I'm working on https://github.com/uroni/hs5 . The S3 API surface is large, but at this point it covers the basics. By limiting the goals I hope it will be maintainable.