SAP Document and Reporting Compliance Greece

We are currently planning an implementation of SAP Document and Reporting Compliance (DRC) for Greece in SAP S/4HANA Cloud Public Edition. As part of our architecture assessment, we would like to clarify whether SAP Integration Suite is a mandatory component for the Greek e-invoicing scenario or whether it can be replaced by a custom-developed middleware solution. Our intention is to retain the standard SAP DRC functionality within SAP S/4HANA Cloud Public Edition, including electronic document generation, processing, and status monitoring, while using our own middleware to communicate with ce