I need to be able to have some apps read/write data in excel workbooks without user interaction. For context, the use case here is an app that automates updating firewall rules across multiple platforms based on data stored in a spreadsheet maintained by a network team. I am running into an issue with the graph API in that I cant access excel data with an app-only token.

I have implemented app-only token auth, but when calling /me/drive/root/children or /me/drive/items/{drive-item-id}/workbook/worksheets('someSheet')/usedRange, or any endpoint I can find to interact with an excel workbook, I am getting “/me request is only valid with delegated authentication flow.”

What is the best way to do this? Is there a set of permissions that I can add to grant access to an excel workbook via an app-only token?
If not, what is there any way to implement delegated authentication flow without user interaction?