We don't support S3 event notifications directly, but you achieve similar functionality by using Database Webhooks [1]. You can trigger any HTTP endpoint or a Supabase Edge function by adding a trigger to the objects table [3] in the Storage schema.
"S3 protocol" typically refers to object storage read/write/delete, not additional service APIs. Support in other S3-compatible vendors varies, often with a different payload (though a translation wrapper shouldn't be too difficult to implement)
[1]: https://supabase.com/docs/guides/database/webhooks [2]: https://supabase.com/docs/guides/functions [3]: https://supabase.com/docs/guides/storage/schema/design