How to change UPF,SMF

Hello, I have successfully set up the core network on my Ubuntu system, but I still have some questions: How can I modify the control plane network element and UPF network element to support Ethernet type of PDU sessions? If you could give me some suggestions, I would greatly appreciate it.

Ethernet PDU session is impossible in free5GC.
In fact, I haven’t found any open source 5G core that supports Ethernet PDU session.

Thank you for your help, but I still have some doubts. The picture is about Free5GC that I saw in a paper. Does the “improvement” here mean improving the network element of Free5GC or other aspects? As I am in the early stage of learning, I do not understand it well. I am looking forward to your reply. Thank you.

Please ask the authors of the referenced paper to upload code here, so that we can use their features.