As someone else says above - it may be encrypted, in which case you’re not going to get anywhere in a useful amount of time. Is the machine still bootable? If so, fire the machine up and find out if the drive has BitLocker or other encryption turned on.
The eMMC “C” drive, right? Would file compression be a problem?
Oh, sure, the machine boots and runs just fine. It’s just a bit slow running off the OS on the eMMC “C” drive. Plus storage is limited, “C” is nearly half of the 64 GB full.
So, check the C drive properties?