Amitai is correct, thanks!
Note that S3 returns a 403 when a file doesn’t exist and the requester doesn’t have permission to list the bucket contents, which may be confusing - this is not a permissions problem. We published the native plugins in 1.1.0 (see Release Native Plugins for 1.1.0 on S3 Production Bucket · Issue #686 · opensearch-project/opensearch-build · GitHub).