we have just created a detailed slide deck which describes the transport functionality within the SAP S/4HANA migration cockpit, direct transfer. This functionality is available since release 2020 OnPrem.
The slide deck also talks about transporting from client to client and system modifiability.
LINK to slide deck.
You are also welcome to visit our so-called landing page – you find there all externally available training material: LINK.
SAP S/4HANA Product Management, Migration Cockpit