with many thanks to Mendy for clarifying, we have learned that there exists an RFC process for submitting to the OpenPOWER ISA WG, which was requested by IBM. this process needs research and documentation as to how to go about it.
Update - FYI I sent an email to the Openpower foundation Hardware Architecture Workgroup asking how to do this and what documents I could share with LibreSOC. I have yet to receive a reply. My understanding of it is that when we want to submit a proposal I just do it. It needs to be in a certain format. The document that I want to share with you is "OpenPOWER HW Architecture WG Charter" (July 2014) - this is about the process of how proposals are made and eventually accepted. This does not have an explicit confidentiality note but is marked "For Discussion Purposes Only OPF HW Arch WG Charter Sub-Commitee" - a phrase about which I wanted some clarification. The HW Architecture Workgroup Discussions is not very busy. The last email was June 2020; 120 since it was started in June 2014.