Hi, @EnterpriseArchitect
Does the KFM migration in your question refer to Redirect and move Windows known folders to OneDrive in this article.
At present, I have not found that these two group policies are related to KFM migration.
“Prevent users from redirecting their Windows known folders to their PC” forces users to keep their Documents, Pictures, and Desktop folders directed to OneDrive.
“Prevent users from changing the location of their OneDrive folder” lets you block users from changing the location of the OneDrive folder on their computer(OneDrive folder default location is under %userprofile%).
Enabling these two group policies means that the user's known folders can only be migrated to OneDrive, and the user cannot change the location of OneDrive.
For details, you can refer to this technical document: Use OneDrive policies to control sync settings
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