I've looked everywhere on the Interweb but couldn't find a satisfying answer...

Does anybody know what "protocol" the AWS S3 speaks?

Our idea is to write a Function for a PLC (no chance to use the provided API) to communicate directly with AWS S3.

For Example PLC to "AWS IoT" works in MQTT/HTTP - how can I skip "AWS IoT"?

I know there is the possibility to put an IoT device inbetween - but we are evaluating our possibilities right now.

Thank you in advance