It's hackable, no piracy yet but CFW is released to some degree, you can run homebrew on any firmware version, backup/restore your NAND, backup your eFuse data and keys, and more. And all without anything more than a piece of wire or a paperclip (though this method isn't recommended, a jig you can get for cheap (£2 cheap) is more reliable and safer)
eFuses are bits of data that are actually burnt into the chip permanently. Every time you update the firmware additional eFuses are burnt. Older firmware will check if eFuses are burnt that aren't supposed to be at that version, and refuse to boot if there's a mismatch.