tl;dr: The author tests six drop-in replacements for MinIO as a single-node local S3 server: S3Proxy and RustFS are the easiest to swap in (though RustFS is alpha and had a recent security vuln), while SeaweedFS and Zenko CloudServer require minor tweaks. Garage and Apache Ozone technically work but are too heavyweight or complex for local demo use, requiring extra init steps or multi-node deployments. Ceph Object Gateway was dismissed for similar reasons.