Hello,
Why don't you create another SharePoint list which is storing your Site info column and Site manager? then you can just get the data from this list and send the alert to this manager only.
Basically, If I will do this, I will have these steps:
Create a new Flow on Power Automate that will be triggered when a new item is added.
Add an an action for getting item for Site Manager based on the value of Site Column.
Then add an action for sending alert to the Site Manager from the above step.
That is my thoughts.
Thanks and hope it can help you.
Mike
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