Apart from all these other products that implement s3? MinIO, Ceph (RGW), Garage, SeaweedFS, Zenko CloudServer, OpenIO, LakeFS, Versity, Storj, Riak CS, JuiceFS, Rustfs, s3proxy.
Riak CS been dead for over a decade which makes me question the rest. Some of these also do not have the same behaviors when it comes to paths (MinIO is one of those IIRC).
Also, none of them implement full S3 API and features.
Add Tigris to the list as well please.
We maintain a page that shows our compatibility with S3 API. It's at https://www.tigrisdata.com/docs/api/s3/. The test runner is open source at https://github.com/tigrisdata-community/s3-api-compat-tests