You can mount (make a drive accessible) in a folder rather than a drive letter if you want. This makes the drive appear as just another folder.
When you mount an internal or external drive in an empty folder, you will be able to access the contents of the drive from the path of the folder. The contents of the drive will still physically be located on the drive. Anything you save into this folder will actually be saved to the drive.
You can mount a drive or volume with or without a drive letter as an empty folder.
This tutorial will show you how to add (assign) or remove (unassign) mount point folder paths for a drive or volume in Windows 11.