How to populate template "Pick List" field type via script

How to populate template "Pick List" field type via script

I am working on a building access service template.

The idea is to have the requester select the Location from a Pick List field and send the approval notification to the Location manager.

Originally I was planning to use the Site(s) information because we already have these populated along with an attribute called "Managed By".  However I have since found out that the Site filed is not available to the requester.
There over 100 locations, so creating a field rule for each location is not realistic.

If I create CMDB Items with the relationship "Managed By", can this be used to populate the template?

Thanks
Sal

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