Hello Derik Oliver,
Thank you for reaching out to Microsoft Support!
We also did the same test, the results are the same as yours, the $filter query parameter does not seem to work, you can give feedback here.
We also recommend that you use the following path instead:
To get a workbook:
https://graph.microsoft.com/v1.0/me/drive/root:/documentSet:/children?$filter=name eq 'Name1.xlsx'
Reference document:
https://learn.microsoft.com/en-us/graph/api/driveitem-list-children?view=graph-rest-1.0&tabs=http
To get a worksheets:
https://graph.microsoft.com/v1.0/me/drive/root:/{item-path}:/workbook/worksheets/{id|name}
Reference document:
https://learn.microsoft.com/en-us/graph/api/worksheet-get?view=graph-rest-1.0&tabs=http
Hope this helps.
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