What can be accessed if phone is lost?

If a phone has not had its bootloader unlocked, has not been rooted, has a finger print lock as well as a pin lock if the fingerprint lock doesn't work. How much can a thief access on the phone? Will they be able to bypass the finger print lock? Will they be able to undelete deleted files in anyway? What can and can they not do on a locked, unrooted, bootloader locked device? The device in question is a Oneplus 2.