Unfortunately, consumer USB flash drives, to my knowledge, do not support SMART commands. So the only conceivable way that I could see to get that information, would be with a mfg's "factory tool" program, to interrogate the flash drive's controller chip, using mfg vendor-specific commands.
Edit: I suppose that a flash drive that supported the more-advanced UASP protocol, might support SCSI's equivalent of SMART data, but as I said, I doubt that standard traditional "Mass Storage Device Class" USB flash drives support reading that info without mfg's tools.