You can stat files in the filesystem. We found some apps were stat'ing some files and these had different dates on different devices and they seemed to be around the time the device would have been manufactured. I can't remember off the top of my head the what the names of the files were.
You can also determine when the last update was installed by stat'ing files in the filesystem. But this is less useful for fingerprinting a device because it is prone to change.
You can also determine when the last update was installed by stat'ing files in the filesystem. But this is less useful for fingerprinting a device because it is prone to change.