what could happen if someone steal your device? physical access to it means lost the money?
or there is a way to enter some kind of pin with the two buttons of the device?
Device can be protected by password.
The seed (few words required to recover your coins on another device or on desktop wallet) is printed on the display during initial configuration (after you buy it). You should store this seed somewhere at safe place, so even if you lost the device or forgot the password, you can recover your coins.