@Viggo Lagerstedt Ekholm Thanks for reaching out. Unfortunately, managed identity is not supported for SharePoint connector. You can always pass your feedback here if this is something you want to see if logic app sharepoint connector.
Leveraging the event grid will not help you in this case as the event source is not SharePoint. The available event sources are documented here.
The alternative would be leveraging the Graph API for SharePoint in logic app using schedule trigger to get the list and check for lastModifiedDateTime property to know if the list was modify recently or not.
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