RoCE (RDMA over Converged Ethernet) and Persistent Memory are features that are supported by Oracle Linux. The minimum version of Oracle Linux required to support RoCE and Persistent Memory is Oracle Linux 7.9.
RoCE is a low-latency, high-bandwidth networking technology that enables fast data transfer between servers using converged Ethernet networks. It is supported by Oracle Linux 7.9 and later versions, which includes the necessary kernel modules and user-space libraries to enable RoCE.
Persistent Memory is a technology that allows data to be stored in non-volatile memory (NVM) devices, such as NVDIMMs (Non-Volatile Dual In-line Memory Modules), which can be accessed at near-DRAM speeds. Oracle Linux 7.9 and later versions include support for Persistent Memory, which includes kernel modules and user-space libraries to enable Persistent Memory.

According to the Oracle Exadata Database Machine X9M Implementation Essentials Official Text Book, the maximum DRAM capacity you can expand an X9M-2 DB Server is 1024GB. This is the maximum amount of DRAM that can be installed in the server. The specific steps for adding DRAM are outlined in the book and can be referenced here: https://docs.oracle.com/cd/E80920_01/E80920/html/x9m_hardware_memory.html.

According to Oracle's documentation1, the customer options for hosting the Platinum Services Advanced Support Gateway are:
Provide individual x86 64-Bit gateway hardware1
Purchase the recommended x86 64-Bit gateway hardware from Oracle1
Install on Oracle Database Appliance2