Subject Matter Expert (SME) and SOP

Answer:
To be precise, I would need much more details, but from the information I have I think you need to set SOM in a way do:
1. define organization that will support all your services (and customer) without duplicating expertise throughout the organization
2. set processes according to the organizational setup i.e. services you support (that includes SOP's)
3. implement tool(s) that will support your activities
4- educate people (bot, SME's and non-SME's)

Here are few articles that can help you:
"5 things to beware of when selecting an ITSM tool" https://advisera.com/20000academy/blog/2016/03/08/5-things-to-beware-of-when-selecting-an-itsm-tool/
"Defining roles and responsibilities for ISO 20000-based IT Service Management" https://advisera.com/20000academy/blog/2017/10/18/defining-roles-and-responsibilities-for-iso-20000-based-it-service-management/
"How to perform ISO 20000 training and awareness" https://advisera.com/20000academy/blog/2017/01/17/how-to-perform-iso-20000-training-and-awareness/

Thank you for enlightening the question. However, from your statement, I need to clarify something:
The organization you mentioned in #1, does it mean "function" according to the question?

What I meant is - if you have 7 functions, and if you have SME in certain technology - use it (one or more persons) for all functions.